Copper alloy sheet for electric and electronic parts

ABSTRACT

A Cu—Fe—P alloy sheet that is provided with the high strength and with the improved resistance of peel off of oxidation film, in order to deal with problems such as package cracks and peeling, is provided. A copper alloy sheet for electric and electronic parts according to the present invention is a copper alloy sheet containing Fe: 0.01 to 0.50 mass % and P: 0.01 to 0.15 mass %, respectively, with the remainder of Cu and inevitable impurities. A centerline average roughness Ra is 0.2 μm or less and a maximum height Rmax is 1.5 μm or less, and Kurtosis (degree peakedness) Rku of roughness curve is 5.0 or less, in measurement of the surface roughness of the copper alloy sheet in accordance with JIS B0601.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of and claims the benefits ofpriority to U.S. application Ser. No. 12/441,904, filed Mar. 19, 2009,which is a national stage of International Application No.PCT/JP2007/068670, filed Sep. 26, 2007. The contents of theseapplications are incorporated herein by reference in their entireties.The International Application is based on and claims the benefits ofpriority to Japanese Patent Application Nos. 2006-270918, 2006-274309,2006-311899 and 2006-311900. The contents of these applications areincorporated herein by reference in their entireties.

TECHNICAL FIELD

The present invention relates to: (1) a Cu—Fe—P alloy sheet with highstrength and with improved resistance of peel off of oxidation film inorder to deal with problems such as package cracks and peeling; (2) aCu—Fe—P alloy sheet with high strength and excellent bendability; (3) aCu—Fe—P alloy sheet with high strength and excellent stampability in astamping process; and (4) a Cu—Fe—P alloy sheet with high strength andexcellent platability. The copper alloy sheet according to the presentinvention is suitable as a material used in lead frames forsemiconductor devices, and also suitably used in electric and electronicparts other than the lead frames for semiconductor devices, such asother semiconductor parts, material used in electric and electronicparts such as printed wiring boards or the like, switching parts, andmechanical parts such as bus bars, terminals, and connectors. However,the following description will be made centering on the case where acopper alloy sheet is used in a lead frame, a semiconductor part, as atypical application example.

BACKGROUND ART

Conventionally, Cu—Fe—P alloy containing Fe and P are generally used asa copper alloy for semiconductor lead frames. Examples of these Cu—Fe—Palloys include, for example, a copper alloy (C19210 alloy) containingFe: 0.05 to 0.15% and P: 0.025 to 0.040%; and a copper alloy (CDA194alloy) containing Fe: 2.1 to 2.6%, P: 0.015 to 0.15%, and Zn: 0.05 to0.20%. When an intermetallic compound such as Fe or Fe—P is precipitatedin a copper matrix, these Cu—Fe—P alloys exhibit high strength, highelectric conductivity, and high thermal conductivity among copperalloys, and therefore these alloys have been used as the internationalstandard alloys.

The recent advancement of the large-capacity, miniaturization, andhigh-performance of semiconductor devices used in electronic apparatuseshas urged the growing reduction in the cross-sectional area of leadframes adopted in the semiconductor devices; thereby, there is a demandfor higher strength, higher electric conductivity, and higher thermalconductivity. With the demand, there is also a demand for higherstrength and higher thermal conductivity to a copper alloy sheet used inlead frames for the semiconductor devices.

On the other hand, plastic packages of semiconductor devices have anadvantage that the package in which a semiconductor chip is sealed by athermosetting resin is excellent in economical efficiency and massproductivity, and therefore they become mainstream. These packages areincreasingly thinner with the recent demand for miniaturization ofelectronic parts.

In assembling the packages, a semiconductor chip is heated to be adheredto a lead frame by using an Ag paste, etc., or soldered or brazed withAg via a plated layer made of Au and Ag or the like. Thereafter, thepackage is generally encapsulated with a resin and subsequentlyconnected to an outer lead by electroplating.

The most serious challenge with respect to the reliability of thesepackages is a package crack or peeling occurring upon implementation.Peeling of a package occurs due to a thermal stress generated in thesubsequent heat treatment, when the adhesion between the resin and thedie pad (portion where a semiconductor chip of a lead frame is mounted)is deteriorated after assembling the semiconductor package.

On the other hand, a package crack occurs through the followingprocesses: a mold resin absorbs moisture from the air after assembling asemiconductor package, and the moisture vaporizes during a heatingprocess in the subsequent implementation; and when a crack is presentinside the package at the time, the moisture is applied to the peelingplane, which acts as an internal pressure; and a swelling is then causedin the package by the inner pressure, or a crack is caused when theresin is weak against the inner pressure . When a crack is caused in apackage after the implementation, moistures and impurities are incursivethereinto cause the chip to be corroded, impairing the function as asemiconductor. In addition, the swelling of a package results in poorappearance and lost of its commodity value. In recent years, suchproblems involving package cracks and peeling have been remarkable withthe above advancement of thinning of the packages.

The problems involving package cracks and peeling are caused by thedeteriorated adhesion between the resin and the die pad. An oxidationfilm of a lead frame base material has the greatest influence on theadhesion between the resin and the die pad. The lead frame base materialhas been subjected to various heating processes for producing sheets orlead frames. Accordingly, an oxidation film with a thickness of tens tohundreds of nanometers is formed on the surface of the base materialbefore a plating process is performed with Ag or the like. On thesurface of the die pad, a copper alloy and the resin are in contact witheach other via the oxidation film, and hence the peeling of theoxidation film from the lead frame base material directly leads to thepeeling between the resin and the die pad, causing adhesion between theresin and the lead frame base material to be remarkably deteriorated.

Accordingly, the problem involving the package crack and the peelingdepends on the adhesion between the oxidation film and the lead framebase material. Therefore, the above Cu—Fe—P alloy sheet with highstrength is required as a lead frame base material to have a highadhesion property with the oxidation film formed on its surface throughvarious heating processes.

In addition, heating temperatures in the above various heating processesfor producing copper alloy sheets and lead frames, are increasinglyhigher for the purposes of improving productivity and efficiency. Forexample, in the lead frame production process, a heat treatment after apress process, etc., is required to be conducted at a higher temperatureand in a shorter time. With such a heating temperature being higher, anew problem arises that the oxidation film formed on a lead frame basematerial tends to peel off from the material more easily due toroughness and fineness of the film, as compared to a previous oxidationfilm that is formed by heating at a lower temperature.

Techniques for improving resistance of peel off of oxidation film havebeen conventionally proposed, although the number of the proposals issmall. For example, it is proposed that crystalline orientation in thesurface layer of a copper alloy is controlled in Patent Document 1. Thatis, Patent Document 1 proposes that, in crystalline orientation in thesurface of a copper alloy base material for lead frames, which isevaluated by the thin film method using an XRD, resistance of peel offof oxidation film can be improved by a ratio of the peak intensity of{100} to the peak intensity of {111} being 0.04 or less. It is notedthat Patent Document 1 includes every kind of copper alloy basematerials for lead frames; however, Cu—Fe—P alloys substantiallyexemplified are only Cu—Fe—P alloys with an Fe content of 2.4% or more,which is a large content.

Taking the surface roughness of a Cu—Fe—P alloy sheet intoconsideration, Patent Documents 2 and 3 propose that resistance of peeloff of oxidation film of the sheet can be improved by making acenterline average roughness Ra 0.2 μm or less and a maximum height Rmax1.5 μm or less, in measurements of the surface roughness. Morespecifically, in Patent Documents 2 and 3, the surface roughness iscontrolled by the type (surface roughness) of a rolling roll in thecold-rolling.

Also in recent years, with increasing applications of Cu—Fe—P alloys andthe advancement of the lightweight, thinning, and miniaturization ofelectric and electronic apparatuses, these copper alloys are alsorequired to have higher strength, higher electric conductivity, andexcellent bendability. As for such bendability, the copper alloys arerequired to endure sharp bending such as U-bending or 90° bending afternotching.

On the other hand, it is conventionally known that bendability can beimproved to some extent by grain refining or by controlling thedispersion state of dispersoids/precipitates (see Patent Documents 4 and5).

In Cu—Fe—P alloys, it is also proposed that the microstructure thereofis controlled in order to improve properties such as bendability. Morespecifically, it is proposed that: a ratio, I(200)/I(220), of theintensity, I(200), of x-ray diffraction of (200) to the intensity,I(220), of x-ray diffraction of (220) is 0.5 or more and 10 or less; ororientation density: D (Cube orientation) of Cube orientation is 1 ormore and 50 or less; or a ratio: D(Cube orientation)/D(S orientation) ofthe orientatin density of Cube orientation to the orientation density ofS orientation, is 0.1 or more and 5 or less (see Patent Document 6).

It is also proposed that a ratio, [I(200)+I(311)/I(220)], of a total ofthe intensity, I(200), of x-ray diffraction of (200) and the intensity,I(311) , of x-ray diffraction of (311) to the intensity, I(220), ofx-ray diffraction of (220) is 0.4 or more (see Patent Document 7).

On the other hand, the copper alloy sheets provided with high strengthare also required to have workability so as to be formed into the leadframes with reduced cross-sectional areas. Specifically, a copper alloysheets are subjected to a stamping process so as to be formed into leadframes, and hence the copper alloy sheets are required to have excellentstampability. The demand also exists in the applications in which thecopper alloy sheets are stamped, other than the application of leadframes.

Conventionally, in order to improve the stampability of Cu—Fe—P alloysheets, techniques for controlling chemical components in which traceadditives such as Pb and Ca are added or a compound that is a startingpoint of a break is dispersed, or techniques in which a grain size,etc., is controlled, have been widely used.

However, these techniques have problems that the controls per se aredifficult to be carried out, these controls adversely affect otherproperties, and therefore a production cost is increased.

On the other hand, it is proposed that the stampability and thebendability of a Cu—Fe—P alloy sheet are improved taking the structurethereof into consideration. For example, Patent Document 8 discloses aCu—Fe—P alloy sheet containing Fe: 0.005 to 0.5 wt %, P: 0.005 to 0.2 wt%, and further either or both of Zn: 0.01 to 10 wt % and/or Sn: 0.01 to5 wt % if needed, with the remainder of Cu and inevitable impurities. InPatent Document 8, the stampability is improved by controlling anintegration degree of crystal orientations of the copper alloy sheet(see Patent Document 8).

More specifically, in Patent Document 8, the integration degree iscontrolled with the use of the fact that: as the copper alloy sheet isrecrystallized and a grain size of the structure becomes larger, anintegration ratio of {200} plane and {311} plane on the sheet surface islarger; and when the copper alloy sheet is rolled, an integration ratioof {220} plane is larger. Characteristically, Patent Document 8 isintended to improve the stampability by increasing an integration ratioof {220} plane on the sheet surface relative to {220} plane and {311}plane. More specifically, assuming that, on the sheet surface, anintensity of x-ray diffraction of {200} plane is I[200], that of {311}plane is I[311], and that of {220} plane is I[220],[I[200]+I[311]]/I[220]<0.4 should be satisfied.

The afore-mentioned Patent Documents 6 and 7 also disclose copper alloysheets of which stampability is improved. (see Patent Documents 6 and7).

Patent Document 9 proposes that I(200)/I(110) should be 1.5 or less inorder to improve the flexibility of a Cu—Fe—P alloy sheet (see PatentDocument 9).

In addition, it is known that, in order to improve the bendability of aCu—Ni—S alloy (Corson alloy), a ratio of the uniform elongation to thetotal elongation, which are among the tensile properties of the copperalloy, is made 0.5 or more, although the copper alloy belongs to anothercopper alloy system (see Patent Document 10).

A copper alloy sheet provided with such high strength is subjected to astamping process and a bending process or the like, followed by beingplated with Ag, etc., and is then formed into lead frames.

However, there sometimes occurs unusual precipitation of the platingpartially (locally) on the surface of the Ag plating or the like, theunusual precipitation being observed by a microscope as a projection ofthe plated layer, like a dot illustrated by the arrow in FIG. 3 (SEMpicture substituting for a drawing, magnification 500) . When suchunusual precipitation of the plating occurs, the lead frame is no longerused as a semiconductor lead frame because a bonding defect is induced.

The unusual precipitation of the plating does not occur on the wholesurface of the plating, nor in a large amount in every semiconductorlead frame to be produced. However, for a highly-efficient massproduction line of semiconductor lead frames, when the unusualprecipitation of the plating occurs in semiconductor lead frames to beproduced, even if the number of the occurrences is very small, i.e., inppm order, there is inevitably a serious influence on the productionspeed and the production efficiency of the line.

At present, the unusual precipitation of the plating is presumed to becaused by the residue of the coarse inclusions (oxides and dispersoids)that are formed in the casting and melting process onto the surfaces ofa final product, or by the surface defects such as coarse pore, whichare formed due to hydrogen. It is because, on the surface of a finalproduct immediately beneath the plating layer where the unusualprecipitation of the plating occurs, coarse inclusions (oxides anddispersoids) or surface defects such as coarse pores formed due tohydrogen, are mostly present and remain.

It is inevitable that a Cu—Fe—P alloy contains hydrogen and oxygen tosome extent during the casing and melting process, and coarse inclusions(oxides and dispersoids) formed in the casting and melting processremain up to a final product sheet and pores formed due to hydrogenappear as surface defects.

Many techniques in which a copper alloy for semiconductor lead frames isprovided with high strength and high formability such as stampabilityand bendability, have conventionally been proposed. However, techniquesin which the platability of a copper alloy for semiconductor leadframes, in particular, the platability of a Cu—Fe—P alloy is improved,and more particularly, the afore-mentioned unusual precipitation of theplating is suppressed, have not been proposed so many.

Among them, a technique in which the platability of a copper alloy sheetis improved by containing Fe: 1.5 to 2.3 wt % or P: 0.015 to 0.045 wt %,which are relatively large amounts, is proposed (Patent Document 11). InPatent Document 11, it is also proposed that intercrystalline cracks areprevented by containing C: 10 to 100 ppm, which is also a relativelylarge amount.

[Patent Document 1] Japanese Patent Laid-Open No. 2001-244400

[Patent Document 2] Japanese Patent Laid-Open No. H2-122035

[Patent Document 3] Japanese Patent Laid-Open No. H2-145734

[Patent Document 4] Japanese Patent Laid-Open No. H6-235035

[Patent Document 5] Japanese Patent Laid-Open No. 2001-279347

[Patent Document 6] Japanese Patent Laid-Open No. 2002-339028

[Patent Document 7] Japanese Patent Laid-Open No. 2000-328157

[Patent Document 8] Japanese Patent Laid-Open No. 2000-328158

[Patent Document 9] Japanese Patent Laid-Open No. 2006-63431

[Patent Document 10] Japanese Patent Laid-Open No. 2002-266042

[Patent Document 11] Japanese Patent No. JP 2962139

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, these conventional techniques are insufficient to ensure such ahigh level of the resistance of peel off of oxidation film as thepresent invention is intended. That is, a new problem that the oxidationfilm on the surface of a lead frame base material formed by heating at ahigh temperature, tends to peel off easily from the material, cannot besolved as a whole by the techniques.

At first, a substantial Fe content of a Cu—Fe—P alloy in Patent Document1 is large exceeding 2.4 mass % at lowest, as stated above. In thispoint, the technique in Patent Document 1 could be indeed effective forimproving resistance of peel off of oxidation film of a Cu—Fe—P alloywith a large Fe content. In fact, the resistance of peel off ofoxidation film of a Cu—Fe—P alloy with an Fe content of 2.41% in Example1 of Patent Document 1, is improved up to 633K (360° C.) at the criticalpeeling temperature of the oxidation film.

However, when an Fe content is large exceeding 2.4 mass %, an oxidationfilm on the surface of a lead frame base material formed by heating at ahigh temperature, tends to peel off more easily from the material. Inaddition, another problem that not only the material properties such aselectric conductivity but also the productivity such as castability areremarkably decreased, arises.

When intending, for example, to increase a precipitation amount of theabove precipitated particles in order to increase electric conductivityforcedly, it causes a problem that the precipitated particles aredeveloped and coarse, resulting in decreased strength and decreasedsoftening resistance. In other words, by the technique in PatentDocument 1, the high strength cannot be compatible with the resistanceof peel off of oxidation film, which are both required of a Cu—Fe—Palloy.

Accordingly, when applying the technique in Patent Document 1 directlyto a Cu—Fe—P alloy that is provided with high strength by a compositionin which an Fe content is substantially reduced to 0.5% or less, theabove resistance of peel off of oxidation film that is requested of alead frame or the like, cannot be obtained.

In the case where the above centerline average roughness Ra is 0.2 μm orless, and the maximum height Rmax is 1.5 μm or less, as with PatentDocuments 2 and 3, resistance of peel off of oxidation film is indeedincreased, as compared to a Cu—Fe—P alloy sheet of which surfaceroughness is more coarse.

However, the present inventors have found that, with respect to theresistance of peel off of oxidation film of an oxidation film that isformed by heating at a higher temperature, which is an object of thepresent invention, there is unexpectedly a significant difference in theresistance of peel off of oxidation film as stated later, even in thecase where the centerline average roughness Ra is equally 0.2 μm orless, and the maximum height Rmax is equally 1.5 μm or less.

This means that an element (factor) other than the centerline averageroughness Ra and the maximum height Rmax, is significantly involved.And, this means that resistance of peel off of oxidation film of anoxidation film that is formed by heating at a higher temperature, whichis an object of the present invention, cannot be improved unless theelement (factor) is controlled.

Addition of solid solution strengthening elements such as Sn and Mg, andincrease in an amount of the work-hardening by the heavy-working with anincrease in a working ratio in the cold-rolling, which are conventionaltechniques for providing high strength to copper alloys, inevitablyentail deterioration of bendability; hence, it is difficult that therequired strength is compatible with the required bendability. However,in order to obtain a Cu—Fe—P alloy having high strength of which tensilestrength is 500 MPa or more, which can be adopted in electric andelectronic parts of the recent light, thin, short, and compact in sizeages, such an increase in an amount of the work-hardening by theheavy-working in the cold-rolling is essential.

In such a Cu—Fe—P alloy with high strength, the bendability cannot beimproved sufficiently for the afore-mentioned sharp bending such asU-bending or 90° bending after notching, only by controlling thestructure of the alloy, such as grain refining or controlling thedispersion state of dispersoids/precipitates, as described in the abovePatent Documents 4 and 5 or the like, and further only by controllingthe microstructure thereof, as described in the above Patent Documents 6and 7 or the like.

The techniques in the Patent Documents 6 or 8 improve stampability byincreasing an integration ratio of {220} plane or {200} plane on thesheet surface. The stampability of a Cu—Fe—P alloy sheet is indeedimproved by increasing an integration ratio of these certain planes.

However, the reduction in the cross-sectional areas of lead frames hasbeen increasingly advancing, which entails increasing advancements ofnarrowing a lead width (from 0.5 mm to 0.3 mm) and thinning a sheetthickness (from 0.25 mm to 0.15 mm) ; hence there is an increasinglystrict demand for the stampability at a stamping process to a Cu—Fe—Palloy sheet with high strength. Accordingly, the effect of improving thestampability by controlling an integration ratio of the structure asdescribed in the above Patent Documents 6 and 8, is insufficient forsatisfying the requested stampability.

And also, the technique for improving benbability of a copper alloysheet as disclosed in the above Patent Document 10, cannot improve therequested stampability. Patent Document 10 handles a Cu—Ni—Si alloy(Corson alloy) of which 0.2 proof stress is at 800 MPa level and ofwhich electric conductivity is at 40% IACS level, which is completelydifferent from a Cu—Fe—P alloy of the present invention in their alloysystems and properties. The bendability and the stampability arecompletely different properties from each other in their mechanisms, andin the case where a ratio of the uniform elongation to the totalelongation is 0.5 or more as with Patent Document 10, the stampabilityof a Cu—Fe—P alloy of the present invention is deteriorated, as statedlater.

In the case where Fe and P are contained in relatively large amounts asis in patent Document 11, an amount of the coarse inclusions (oxides anddispersoids) that are formed in the casting and melting process islarge, and the inclusions remain in a large amount onto the surface of afinal product, and therefore the above unusual precipitation of theplating are adversely induced.

In addition, the technique in Patent Document 11 does not take surfacedefects such as pores formed due to hydrogen into consideration, whichare a cause of the unusual precipitation of the plating; therefore, theunusual precipitation of the plating due to the defects cannot beprevented.

In addition, the technique in Patent Document 11 is intended to containC in a large amount of 10 to 100 ppm by adding an Fe—C base alloy in amelt stream, in a copper sheet production process. However, C is easy todisperse, and thereby disperses at the moment of being added in a melt;hence, it is usually very difficult to contain C in an amount of 10 ppmor more in a melt. In addition, the present inventors have found that,in a Cu—Fe—P alloy with a large C content, the unusual precipitation ofthe plating is adversely promoted, as stated later.

Accordingly, the techniques effective for preventing the afore-mentionedunusual precipitation of the plating have not been proposed so much, sofar. Therefore, in order to prevent the above unusual precipitation ofthe plating in the sheets including Cu—Fe—P alloys, contents of hydrogenand oxygen or the like, which causes the unusual precipitation of theplating, are generally to be reduced more actively in the casting andmelting process.

However, it becomes a major factor for raising a production cost or fordecreasing a production efficiency of a copper alloy production processthat contents of hydrogen and oxygen or the like are reduced moreactively to extremely small amounts in the copper alloy productionprocess, in particular, in the casting and melting process, etc.Accordingly, it is inevitable that a Cu—Fe—P alloy contains hydrogen andoxygen to some extent in the casting and melting process.

Accordingly, it is also inevitable that, in a Cu—Fe—P alloy, coarseinclusions (oxides and dispersoids) formed in the casting and meltingprocess remain up to a final product sheet, and a pore formed due tohydrogen appears as a surface defect.

Accordingly, a Cu—Fe—P alloy sheet is needed in which theafore-mentioned unusual precipitation of the plating can be prevented,even when hydrogen and oxygen are contained to some extent in thecasting and melting process.

The present invention has been made in order to solve these problems,and an object of the invention is to provide a Cu—Fe—P alloy sheet inwhich high strength is compatible with excellent resistance of peel offof oxidation film of an oxidation film formed by heating at a highertemperature. Another object of the present invention is to provide aCu—Fe—P alloy sheet in which high strength is compatible with excellentbendability. Another object of the present invention is to provide aCu—Fe—P alloy sheet in which high strength is compatible with excellentstampability. Moreover, another object of the present invention is toprovide a Cu—Fe—P alloy sheet in which high strength is compatible withexcellent platability for preventing unusual precipitation of theplating.

Means for Solving the Problems

In order to attain the afore-mentioned objects, the gist of a copperalloy sheet for electric and electronic parts according to the presentinvention, is a copper alloy sheet containing Fe: 0.01 to 0.50 mass %and P: 0.01 to 0.15 mass %, respectively, with the remainder of Cu andinevitable impurities, wherein a centerline average roughness Ra is 0.2μm or less and a maximum height Rmax is 1.5 μm or less, and Kurtosis(degree of peakedness) Rku of roughness curve is 5.0 or less, inmeasurement of the surface roughness of the copper alloy sheet inaccordance with JIS B0601.

In the copper alloy sheet for electric and electronic parts according tothe present invention, r value parallel to the rolling direction of thecopper alloy sheet is preferably 0.3 or more.

In the copper alloy sheet for electric and electronic parts according tothe present invention, the tensile modulus thereof is preferably morethan 120 GPa, and a ratio of the uniform elongation to the totalelongation is preferably less than 0.50, wherein the two measurementsare determined by a tensile test using a test piece taken the widthdirection of the alloy sheet, which is perpendicular to the rollingdirection of the sheet, as the longitudinal direction of the test piece.

The copper alloy sheet for electric and electronic parts according tothe present invention preferably further contains C: 3 to 15 ppm, andcontents of O and H are preferably regulated so as to be 40 ppm or lessand 1.0 ppm or less, respectively.

The copper alloy sheet according to the present invention may furthercontain Sn: 0.005 to 5.0 mass % in order to attain high strength, orfurther contain Zn: 0.005 to 3.0 mass % in order to improve softeningresistance of peel off of the soldering and the Sn plating,respectively.

In the copper alloy sheet according to the present invention, bothcontents of S and Pb are preferably further regulated so as to be 20 ppmor less, respectively.

In the copper alloy sheet according to the present invention, tensilestrength thereof is preferably 500 MPa or more, and hardness thereof ispreferably 150 Hv or more.

The copper alloy sheet according to the present invention may furthercontain a total content of 0.0001 to 1.0 mass % of one or more elementsselected from Mn, Mg, and Ca.

The copper alloy sheet according to the present invention may furthercontain a total content of 0.001 to 1.0 mass % of one or more elementsselected from Zr, Ag, Cr, Cd, Be, Ti, Co, Ni, Au, and Pt.

The copper alloy sheet according to the present invention may furthercontain a total content of 0.0001 to 1.0 mass % of one or more elementsselected from Mn, Mg, and Ca; and contain a total content of 0.001 to1.0 mass % of one or more elements selected from Zr, Ag, Cr, Cd, Be, Ti,Co, Ni, Au, and Pt, respectively, wherein a total content of thesecontained elements is 1.0 mass % or less.

The copper alloy sheet according to the present invention preferablyfurther contains a total content of 0.1 mass % or less of Hf, Th, Li,Na, K, Sr, Pd, W, S, Si, C, Nb, Al, V, Y, Mo, Pb, In, Ga, Ge, As, Sb,Bi, Te, B, and misch metal.

Also, in order to attain the afore-mentioned objects, the gist of thecopper alloy sheet for electric and electronic parts according to thepresent invention, is a copper alloy sheet containing Fe: 0.01 to 0.50mass % and P: 0.01 to 0.15 mass %, respectively, with the remainder ofCu and inevitable impurities, wherein tensile strength thereof is 500MPa or more and the hardness thereof is 150 Hv or more, and r valueparallel to the rolling direction of the copper alloy sheet is 0.3 ormore.

Also, in order to attain the afore-mentioned objects, the gist of thecopper alloy sheet for electric and electronic parts according to thepresent invention, is a copper alloy sheet containing Fe: 0.01 to 0.50mass % and P: 0.01 to 0.15 mass %, respectively, with the remainder ofCu and inevitable impurities, wherein tensile strength thereof is morethan 120 GPa and a ratio of the uniform elongation to the totalelongation is less than 0.50, the two measurements being determined by atensile test using a test piece taken the width direction of the alloysheet, which is perpendicular to the rolling direction of the sheet, asthe longitudinal direction of the test piece.

Also, in order to attain the afore-mentioned objects, the gist of thecopper alloy sheet for electric and electronic parts according to thepresent invention, is a copper alloy sheet containing Fe: 0.01 to 0.50mass %, P: 0.01 to 0.15 mass %, and C: 3 to 15 ppm, respectively,wherein contents of O and H are regulated so as to be 40 ppm or less and1.0 ppm or less, respectively.

The copper alloy sheet according to the present invention can be used invarious electric and electronic parts, in particular, preferably used inthe application of the semiconductor lead frames, semiconductor parts.

Effects of the Invention

The copper alloy sheet according to the present invention has tensilestrength of 500 MPa or more and hardness of 150 Hv or more, as aguideline of the high strength. It is noted that electric conductivityin a copper alloy sheet is correlated with strength of the sheet, and inthe present invention, electric conductivity is also inevitably lower asthe sheet has higher strength; however, there is no trouble in practicalapplication. Accordingly, the high electric conductivity mentionedherein means that the sheet has relatively high electric conductivityfor high strength.

In the present invention, resistance of peel off of oxidation film isimproved by controlling Kurtosis (degree of peakedness) Rku of roughnesscurve of a Cu—Fe—P alloy sheet with high strength and with an oxidationfilm formed by heating at a higher temperature.

As shown by the equation described later, Kurtosis (degree ofpeakedness) Rku of roughness curve is defined in the measurement ofsurface roughness JIS B 0601 and is known, which indicates thepeakedness of the concavities and convexities of surface roughness(curve of a rolling circle waviness profile Z(x)).

For example, as illustrated in FIG. 1( a), when Rku is large exceeding5.0, the concave-convex curve of surface roughness (curve of a rollingcircle waviness profile Z(x)) is sharp, or precipitous. On the otherhand, as illustrated in FIG. 1( b), when Rku is small, that is, 5.0 orless, as is in the present invention, the concave-convex curve ofsurface roughness (curve of a rolling circle waviness profile Z(x)) isrelatively rounded, or smooth.

According to the knowledge of the present inventors, resistance of peeloff of oxidation film of an oxidation film of a Cu—Fe—P alloy sheet thatis formed by heating at a higher temperature, can be more improved whenthe concave-convex curve of surface roughness (curve of a rolling circlewaviness profile Z(x)) is relatively rounded, or smooth.

Herein, it is thought that resistance of peel off of oxidation film islikely to be more improved when the concave-convex curve of surfaceroughness is sharp, or precipitous, with Rku exceeding 5.0 as is in FIG.1( a), because an anchor effect is more demonstrated in the case. Withrespect to this point, it is presently still unknown why resistance ofpeel off of oxidation film of an oxidation film of a Cu—Fe—P alloy sheetthat is formed by heating at a higher temperature, is more improved whenthe concave-convex curve of surface roughness is relatively rounded, orsmooth, as illustrated in FIG. 1( b).

In the present invention, however, resistance of peel off of oxidationfilm of an oxidation film of a Cu—Fe—P alloy sheet that is formed byheating at a higher temperature, can be more improved by the simplemeasures to control Kurtosis (degree of peakedness) Rku of roughnesscurve of a copper alloy sheet with a Cu—Fe—P system composition, withoutusing a conventional technique in which a large content of Fe causesanother problem.

In the present invention, Kurtosis (degree of peakedness) Rku ofroughness curve of a copper alloy sheet is a technical element that isindependent from the centerline average roughness Ra and the maximumheight Rmax. That is, as described in the afore-mentioned PatentDocuments 2 and 3, even in the case where the surface of a copper alloysheet is smoothed by a centerline average roughness Ra being 0.2 μm orless and a maximum height Rmax being 1.5 μm or less, there are caseswhere Rku exceeds 5.0 and where Rku is 5.0 or less.

In other words, even when the surface of a copper alloy sheet issmoothed by making a centerline average roughness Ra 0.2 μm or less anda maximum height Rmax 1.5 μm or less, Rku is not inevitably 5.0 or less,and there is a high probability that Rku is out of the range or largerthan that. Accordingly, even when a centerline average roughness Ra is0.2 μm or less and a maximum height Rmax is 1.5 μm or less, it is quiteunknown whether Rku of the surface of the copper alloy sheet is 5.0 orless, unless Rku is actually measured.

This fact is supported by the fact that there is a significantdifference in resistance of peel off of oxidation film of an oxidationfilm of a Cu—Fe—P alloy that is formed by heating at a highertemperature, in accordance with Kurtosis (degree of peakedness) Rku ofroughness curve, even when a centerline average roughness Ra and amaximum height Rmax are the same, as stated later. This fact is alsosupported by the fact that Rku cannot be controlled so as to be 5.0 orless by the physical processing such as conventional control of thesurface roughness of a rolling roll, as described in Patent Documents 2and 3, but can be controlled by a cleaning treatment entailing chemicaletching, as stated later.

According to the present invention, bendability of a Cu—Fe—P alloy sheetcan be improved by making r value parallel to the rolling direction ofthe sheet a constant value that is 0.3 or more, even for a copper alloysheet with high strength of which tensile strength is 500 MPa or more.

Herein, it is known that, in the fields of steel sheets and aluminumalloy sheets other than copper sheets, bendability thereof is improvedby increasing r value thereof, even for a steel sheet or an aluminumsheet with high strength. However, it is not necessarily known that, incopper alloys, in particular, a Cu—Fe—P alloy sheet, bendability thereofis improved taking r value thereof into consideration.

The reason is presumed to be as follows: as stated with respect to theconventional techniques, in the field of Cu—Fe—P alloy sheets, it hasbeen mainstream that bendability of the sheets is improved by grainrefining, or by controlling crystal orientation distribution density ofthe copper alloy sheet, such as controlling the dispersion state ofdispersoids/precipitates and controlling the microstructure thereof .The reason is also presumed to be as follows: there is a commonknowledge that, in a Cu—Fe—P alloy sheet, a factor other than r valuehas a significant influence on improving bendability, and r value is notso effective for improving bendability.

As stated above, in a Cu—Fe—P alloy sheet in which contents of solidsolution strengthening elements are strictly limited, unlike otherCorson alloys, an amount of the work-hardening by the heavy-working withan increase in a working ratio in the cold-rolling should be carried outin order to provide high strength to a Cu—Fe—P alloy sheet.

In the heavy-working in the cold-rolling, a copper alloy sheet naturallyhas significant anisotropy of crystal orientation in which grain size issignificantly elongated in the rolling direction. Therefore, it is knownthat bendability, in particular, parallel to the rolling direction, isremarkably deteriorated. Accordingly, it naturally becomes a majorconcern among persons skilled in the art that the significant anisotropyof the crystal orientation, that is, the crystal orientationdistribution density of the copper alloy sheet is to be controlled inorder to improve bendability.

However, in such control of the crystal orientation distribution densityof a copper alloy sheet, it is very difficult to control each crystalorientation so as to have a desired distribution density in order toobtain the desired bendability, that is, to actually produce such acopper alloy sheet.

On the other hand, the present invention improves bendability of aCu—Fe—P alloy sheet by increasing r value of the sheet, even for acopper alloy sheet with high strength. The r value is also referred toas a plastic strain ratio, indicating a reduction ratio of a sheetthickness to a sheet width in a tensile test of a material such as aCu—Fe—P alloy sheet. As a reduction ratio of a sheet thickness to asheet width of a material is smaller, r value is larger. With respect tothe point, bendability is also better as a reduction ratio of a sheetthickness to a sheet width is smaller; hence, as r value is larger, amaterial such as a Cu—Fe—P alloy sheet, is more difficult to break andbendability thereof is more improved.

Such correlation or consequence between bendability and r value is alsosupported by the fact that r value is an index indicating the plasticanisotropy, as already known, and has a close relation with the abovecrystal orientation distribution density.

However, even if there is a correlation between bendability and r valuein a Cu—Fe—P alloy sheet, it is a completely different issue whether ther value has an effect of actually improving bendability, as statedabove. And, it is also a completely different issue whether the r valuecan be improved to the extent where bendability is improved. That is, ina Cu—Fe—P alloy sheet, it is an unknown issue whether bendabilitythereof can be improved by increasing r value, unless actuallyperformed.

With respect to the point, in the present invention, r value parallel tothe rolling direction of a Cu—Fe—P alloy sheet is made larger or equalto a constant that is 0.3 or more, by a specific technique (measures) inwhich the low-temperature annealing after the cold-rolling is performedby continuous annealing, and at the time, an appropriate tension isapplied to a passing sheet, as stated later. Thereby, bendability of thesheet can be improved, even for a copper alloy sheet with high strengthof which tensile strength is 500 MPa or more.

In the present invention, it has been found that, in a Cu—Fe—P alloysheet with high strength of which tensile strength is 500 MPa or more,tensile properties such as the tensile modulus and a ratio of theuniform elongation to the total elongation, which are determined by atensile test, have significant influence on stampability rather thancontrol of the microstructure of the sheet as described in PatentDocuments 6 and 8.

As the tensile modulus determined by a tensile test is larger,stampabillity is more improved. Also, as a ratio of the uniformelongation to the total elongation is smaller, stampability is moreimproved. However, these tensile properties specified by the presentinvention are presently unknown with respect to a clear correlation withthe structure of a Cu—Fe—P alloy sheet, that is, the state ofprecipitates (amount or size of precipitates), or the microstructure orthe like. Accordingly, in the present invention, the structure of aCu—Fe—P alloy sheet is difficult to be specified qualitatively andquantitatively, as a requirement for improving stampability.

These tensile properties specified by the present invention arenaturally affected greatly by a component composition of a Cu—Fe—P alloysheet, and also affected greatly by the production processes and theproduction conditions; hence, they cannot be determined only by acomponent composition. That is, these tensile properties specified bythe present invention are greatly affected by the production processesand the production conditions of a Cu—Fe—P alloy sheet such as ahomogenization heat treatment or a heating treatment prior to thehot-rolling, temperature at the start of cooling with water after thehot-rolling, temperature of the intermediate annealing, and line speedduring the final continuous annealing, as stated later.

These tensile properties specified by the present invention aredifficult to be obtained by the batch-type final annealing, that is,difficult to be obtained unless the continuous annealing is performed inwhich a sheet (coil) continuously passes through a furnace and isprocessed.

Accordingly, in the present invention, a Cu—Fe—P alloy sheet isspecified by the tensile properties such as the tensile modulus and aratio of the uniform elongation to the total elongation as well as acomponent composition, in order to ensure the good stampability thereof,as stated above.

The present invention is primarily characterized by containing carbon(C) in an extremely small amount in terms of absolute amount, thecontent being larger or equal to that of being contained naturally.

In the present invention, the contained carbon serves as suppressingagglomeration of oxygen (O) and hydrogen (H), which are present in aCu—Fe—P alloy sheet, and as increasing starting points of inclusions andpores. The carbon also serves as making the sizes of the formedinclusions and pores fine, and as preventing that these inclusions andpores become starting points (causes) where the above unusualprecipitation of the plating originate. As a result, high strength iscompatible with excellent platability by which the unusual precipitationof the plating is prevented, in a Cu—Fe—P alloy sheet.

However, in order to ensure the operation effect of C , higher limits ofcontents of O and H present in a Cu—Fe—P alloy sheet are specified as apremise as well as a C content.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustrative diagram illustrating Kurtosis (degree ofpeakedness) Rku of roughness curve in the surface roughness of a copperalloy sheet, which is specified by the present invention.

FIG. 2 is an illustrative diagram illustrating a method for measuring ashear plane ratio.

FIG. 3 is a picture of the surface of a copper alloy sheet illustratingunusual precipitation of the plating, which is a substitute for adrawing.

DESCRIPTION OF SYMBOLS

1: COPPER ALLOY SHEET

2: STAMPED HOLE

3: CUTTING PLACE

BEST MODE FOR CARRYING OUT THE INVENTION

Importance of each requirement for satisfying required properties of aCu—Fe—P alloy sheet according to the present invention used forsemiconductor lead frames or the like, and embodiments of the inventionwill be described specifically below.

First Embodiment: Cu—Fe—P Alloy Sheet with High Strength and ImprovedResistance of Peel Off of Oxidation Film in Order to Deal with Problemsof Package Cracks and Peeling (Surface Roughness)

In the present invention, as a prerequisite requirement of the surfaceroughness of a Cu—Fe—P alloy sheet, a centerline average roughness Rashould be 0.2 μm or less and a maximum height Rmax should be 1.5 μm orless, in measurement of the surface roughness of the copper alloy sheetin accordance with JIS B06061. The centerline average roughness Ra ispreferably 0.1 μm or less and the maximum height Rmax is preferably 1.0μm or less.

When the centerline average roughness Ra exceeds 0.2 μm, or the maximumheight Rmax exceeds 1.5 μm, the surface of the Cu—Fe—P alloy sheet istoo coarse rather than smooth, impairing the basic properties requestedof a lead frame. That is, heating adhesion of a semiconductor chip to alead frames by using Ag paste, etc., plating process of Au and Ag, etc,or soldering or brazing with Ag, etc., are impaired. Further, it becomesdifficult that Rku of the surface of a Cu—Fe—P alloy sheet is controlledso as to be 5.0 or less by a cleaning treatment entailing chemicaletching.

(Rku)

In the present invention, Kurtosis (degree of peakedness) Rku ofroughness curve in measurement of the surface roughness of a Cu—Fe—Palloy sheet, in accordance with JIS B0601, should be 5.0 or less basedon the above prerequisite requirement, in order to improve resistance ofpeel off of oxidation film of an oxidation film of the sheet that isformed by heating at a higher temperature. When Rku exceeds 5.0,resistance of peel off of oxidation film of an oxidation film of aCu—Fe—P alloy sheet that is formed by heating at a higher temperature,cannot be improved. Rku is preferably 4.5 or less.

In JIS B0606, Kurtosis (degree of peakedness) Rku of roughness curve isdefined as follows, as represented by the following equation: afourth-power average of a curve of a rolling circle waviness profileZ(x) with respect to the reference length lr on the surface of an itemto be measured, is divided by a fourth-power of the root mean square Rq.

$\begin{matrix}{{Rku} = {\frac{1}{{Rq}^{4}}\left\lbrack {\frac{1}{l\; r}{\int_{0}^{l\; r}{{Z^{4}(x)}\ {x}}}} \right\rbrack}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

As illustrated in FIG. 1, the Rku represents a characteristic averageparameter in the height direction of a concave-convex curve of thesurface roughness (curve of a rolling circle waviness profile Z(x)).

The characteristic in the height direction is represented by a degree ofpeakedness; and when Rku is large exceeding 5.0, a concave-convex curveof the surface roughness (curve of a rolling circle waviness profileZ(x)) is sharp, or precipitous, as illustrated in FIG. 1( a). On theother hand, when Rku is small, that is, 0.5 or less, as is in thepresent invention, a concave-convex curve of the surface roughness isrelatively rounded, or smooth, as illustrated in FIG. 1( b).

On the other hand, the above centerline average roughness Ra is, whenmentioned with respect to the concave-convex curve of the surfaceroughness in FIGS. 1( a) and 1(b), an average parameter of amplitudeheights in the height direction, and the above maximum height Rmax is aparameter of the maximum height of amplitudes in the height direction,both of which are widely used as indexes of the surface roughness.Accordingly, it can be understood that Rku of the present invention isan independent value that is never associated with the centerlineaverage roughness Ra and the maximum height Rmax, and as illustrated inFIGS. 1( a) and 1(b) , Rkus are greatly different even if Ras and Rmaxsare the same.

In JIS 50601, as what indicate the characteristic average parameters inthe height direction, there are Pku: Kurtosis (degree of peakedness) ofprofile curve and Wku: Kurtosis (degree peakedness) of waviness curve,etc., other than Rku. However, these Pku and Wku are less correlativewith the resistance of peel off of oxidation film of an oxidation filmof a Cu—Fe—P alloy sheet that is formed by heating at a highertemperature, than Rku of the present invention. Accordingly, in thepresent invention, Rku is selected to be specified by the presentinvention, among the characteristic average parameters in the heightdirection of the surface roughness (curve).

In the present invention, the surface of a Cu—Fe—P alloy sheet is atfirst controlled by the physical processing such as control of thesurface roughness of a rolling roll, such that a centerline averageroughness Ra is 0.2 μm or less and a maximum height Rmax is 1.5 μm orless. Subsequently, Rku is made 5.0 or less by a cleaning treatmententailing chemical etching, as stated later.

(r Value)

In the present invention, r value parallel to the rolling direction of acopper alloy sheet is preferably 0.3 or more. With the r value being 0.3or more in this way, a copper alloy sheet that is further provided withexcellent bendability in addition to the above properties, can beobtained. A method for measuring r value or the like will be describedlater.

(Tensile Module, Uniform Elongation/Total Elongation)

In the present invention, the tensile modulus thereof is preferably morethan 120 GPa, and a ratio of the uniform elongation to the totalelongation is preferably less than 0.50, wherein the two measurementsare determined by a tensile test using a test piece taken the widthdirection of the alloy sheet, which is perpendicular to the rollingdirection of the sheet, as the longitudinal direction of the test piece.By further provided with these features, a copper alloy sheet that isfurther provided with excellent stampability in addition to the aboveproperties, can be obtained. The tensile modulus and the uniformelongation/the total elongation will be described in detail later.

(Component Composition of Copper Alloy Sheet)

In the present invention, a copper alloy sheet preferably has basicproperties as a material used for semiconductor lead frames or the like,such as the high strength of which tensile strength is 500 MPa or more,and the hardness of 150 Hv or more or the like. The copper alloy sheetaccording to the present invention has excellent platability by whichthe unusual precipitation of the plating are prevented, in addition tosatisfying these basic properties, or on the premise that these basicproperties are not deteriorated. For this purpose, the Cu—Fe—P alloysheet has a basic composition containing: Fe: 0.01 to 0.50% and P: 0.01to 0.15%, with the remainder of Cu and inevitable impurities.

The copper alloy sheet may further selectively contain elements such asZn and Sn, which will be described later, relative to the basiccomposition. It is also acceptable that the copper alloy sheet containselements (impurity elements) other than the described elements, as faras they do not impair the properties of the present invention. It isnoted that all of the contents of alloy elements and impurity elementsare represented by mass %.

(Fe)

Fe is a major element that precipitates as Fe or a Fe-groupintermetallic compound to increase strength and softening resistance ofa copper alloy. When an Fe content is too small, precipitation of acompound is insufficient and contribution to the increase in thestrength is insufficient, resulting in decreased strength even if thefinal cold-rolling is performed under the heavy-working conditions,while improvement of electric conductivity is satisfied. On the otherhand, when an Fe content is too large, electric conductivity isdecreased. In addition, strength and softening resistance are adverselydeteriorated. Accordingly, an Fe content should be within the range of0.01 to 0.50%, preferably 0.15 to 0.35%.

(P)

P is a major element serving as forming a compound with Fe to increasestrength of a copper alloy, in addition to having a deoxidizing action.When a P content is too small, precipitation of a compound isinsufficient, and contribution to increase in the strength isinsufficient, resulting in decreased strength even if the finalcold-rolling is performed under the heavy-working conditions, whileimprovement of electric conductivity is satisfied. On the other hand,when a P content is too large, not only electric conductivity but alsohot workability are deteriorated, causing a crack to easily occur.Accordingly, a P content should be within the range of 0.01 to 0.15%,preferably 0.05 to 0.12%.

(C, O, H)

In the present invention, the copper alloy sheet preferably furthercontains C: 3 to 15 ppm, and contents of O and H are preferablyregulated so as to be 40 ppm or less and 1.0 ppm or less, respectively.With contents of C, O, and H being within the above ranges, a copperalloy sheet that is further provided with excellent platability inaddition to the above properties, can be obtained. Contents of C, O, andH will be described in detail later.

(Zn)

Zn improves softening resistance of peel off of the soldering and the Snplating of a copper alloy, which are essential for lead frames or thelike; therefore, Zn is an element to be optionally added when theseeffects are needed. When a Zn content is less than 0.005%, a desiredeffect cannot be obtained. On the other hand, when exceeding 3.0%, notonly solder wettability is deteriorated but also electric conductivityis significantly decreased. Accordingly, a Zn content should, whenoptionally contained, be selected within the range of 0.005 to 3.0% inaccordance with (in consideration of) the balance between the electricconductivity and the softening resistance of peel off of the solderingand the Sn plating that are requested of the application.

(Sn)

Sn contributes to an increase in strength of a copper alloy; therefore,Sn is an element to be optionally added when the effect is needed. Whenan Sn content is less than 0.001%, it does not contribute to providinghigh strength. On the other hand, when an Sn content is large, theeffect of Sn is saturated to conversely incur a decrease in electricconductivity. Accordingly, an Sn content should, when optionallycontained, be selected within the range of 0.001 to 5.0% in accordancewith (in consideration of) the balance between the strength (hardness)and the electric conductivity that are requested of the application.

(S, Pb)

In the copper alloy sheet according to the present invention, it ispreferable that both contents of S and Pb are regulated so as to be 20ppm or less, respectively. S and Pb impair not only the basic propertiesnecessary when used in semiconductor lead frames or the like, such asstrength, hardness, and electric conductivity, but also the Agplatability.

(Contents of Mn, Mg, Ca)

Mn, Mg, and Ca contribute to improvement of hot workability of a copperalloy; hence, these elements are optionally contained when the effect isneeded. When a total content of one or more elements selected from Mn,Mg, and Ca is less than 0.0001%, a desired effect cannot be obtained. Onthe other hand, when a total content thereof exceeds 1.0%, not onlystrength and softening resistance of a copper alloy are decreased butalso electric conductivity is drastically decreased, due to generationof coarse dispersoids and oxides. Accordingly, these elements should beoptionally contained in a total content of 0.0001 to 1.0%.

(Contents of Zr, Ag, Cr, Cd, Be, Ti, Co, Ni, Au, Pt)

These elements are effective for increasing strength of a copper alloy;hence, they are optionally contained when the effect is needed. When atotal content of one or more elements selected from these elements isless than 0.001%, a desired effect cannot be obtained. On the otherhand, when a total content thereof exceeds 1.0%, it is not preferablebecause not only strength and softening resistance of a copper alloy aredecreased but also electric conductivity is drastically decreased due togeneration of coarse dispersoids and oxides. Accordingly, these elementsshould be optionally contained in a total content of 0.001 to 1.0%. Whenthese elements are contained in conjunction with the above Mn, Mg, andCa, a total content of these contained elements should be 1.0% or less.

(Contents of Hf, Th, Li, Na, K, Sr, Pd, W, Si, Nb, Al, V, Y, Mo, In, Ga,Ge, As, Sb, Bi, Te, B, and Misch Metal)

These elements are impurity elements, and when a total content of theseelements exceeds 0.1%, strength and softening resistance thereof aredecreased due to generation of coarse dispersoids and oxides.Accordingly, a total content of these elements is preferably 0.1% orless.

(Production Condition)

Preferable production conditions for making the structure of a copperalloy sheet compatible with the above-described structure specified bythe present invention, will be described below. The copper alloy sheetaccording to the present invention does not require the normalproduction process per se to be changed drastically and can be producedthrough the same process as the normal one, except the preferablecold-rolling and cleaning conditions for controlling the afore-mentionedRa, Rmax, and Rku of the surface of the copper alloy sheet, which willbe described later.

That is, a copper alloy melt adjusted so as to have the above-describedpreferable component composition is at first cast. An obtained ingot issubjected to facing, and to a heat treatment or a homogenization heattreatment, and then to hot-rolling, followed by cooling with water. Thehot-rolling may be performed under the normal conditions.

Thereafter, primary cold-rolling referred to as intermediate rolling isperformed, followed by annealing and cleaning, and still further byfinish (final) cold-rolling and low-temperature annealing (finalannealing, finish annealing), such that a copper alloy sheet or the likehaving a product sheet thickness is produced. These annealing andcold-rolling may be performed repeatedly. For example, in the case of acopper alloy sheet used in semiconductor materials for lead frames orthe like, a product sheet thickness is about 0.1 to 0.4 mm.

A solution treatment and a quenching treatment by water-cooling of thecopper alloy sheet may be performed before the primary cold-rolling. Atthe time, a solution treatment temperature is selected, for example,within the range of 750 to 1000° C.

(Final Cold-Rolling)

The final cold-rolling is also performed in the normal process. In orderto provide the tensile strength of 500 MPa or more and the hardness of150 Hv or more to a Cu—Fe—P alloy sheet in which the contents of solidsolution strengthening elements are strictly limited, a working-ratio inthe final cold-rolling is determined on the side of the heavy-working ina relation with the working ratio in the cold-rolling so far.

A minimum reduction ratio per one pass (cold-rolling ratio) in the finalcold-rolling is preferably 20% or more. When a minimum reduction ratioper one pass in the final cold-rolling is less than 20%, a thicknessstrain becomes large, resulting in deteriorated bendability.

In the final cold-rolling, the surface roughness of a rolling roll to beused is controlled such that, on the surface of a Cu—Fe—P alloy sheet, acenterline average roughness Ra is 0.2 μm or less and a maximum heightRmax is 1.5 μm or less.

Specifically, a bright roll (surface polished roll) is used in which acenterline average roughness Ra and a maximum height Rmax of the surfaceroughness of the rolling roll is fined so as to be 0.2 μm or less and1.5 μm or less, respectively, in the same way as the surface of therolled copper alloy sheet.

(Final Annealing)

In the Cu—Fe—P alloy sheet of which surface is controlled such that acenterline average roughness Ra is 0.2 μm or less and a maximum heightRmax is 1.5 μm or less in the final cold-rolling, the final annealing ispreferably performed in a continuous heat treatment furnace. The finishannealing is preferably performed under a low-temperature condition of100 to 400° C. for 0.2 minutes or more and 300 minutes or less. In theusual production process for producing a copper alloy sheet used fortypical lead frames, the final annealing is not performed after thefinal cold-rolling in order to avoid a decrease in strength, except theannealing for relieving a stress (350° C. for about 20 seconds) . In thepresent invention, however, the decrease in strength can be suppressedby the above-described cold-rolling conditions and by a loweredtemperature in the final annealing. And, bendability or the like can beimproved by performing the final annealing at a low-temperature.

When an annealing temperature is lower than 100° C., or an annealingtime is less than 0.2 minutes, or this low-temperature annealing is notperformed, there is a high probability that the structure and propertiesof the copper alloy sheet are hardly changed from the state after thefinal cold-rolling. Conversely, when the annealing is performed at atemperature exceeding 400° C., or the annealing is performed for morethan 300 minutes, recrystallization occurs, rearrangement and recoveryphenomena of the dislocation occur excessively, and precipitates becomecoarse; therefore, there is a high probability that stampability andstrength of the sheet are decreased.

(Cleaning Treatment)

The surface of the Cu—Fe—P alloy sheet is controlled such that Rku is5.0 or less by a cleaning treatment entailing chemical etching after thefinal annealing. In the cleaning treatment, commercially availabledetergents can be appropriately used, as far as the cleaning treatmententails chemical etching by which Rku is ensured to be 5.0 or less.

As a measure to ensure that Rku is 5.0 or less, a cleaning treatmententailing acid etching is preferable in which a copper alloy sheet isdipped in an aqueous sulfuric acid solution (room temperature) with aconcentration of 5 to 50 mass % for 1 to 60 seconds. When aconcentration of sulfuric acid is less than 5 mass % and a dipping timeis less than 1 second, cleaning or etching of the matrix surface isinsufficient, and hence there is a high probability that Rku cannot be5.0 or less. On the other hand, when a concentration of sulfuric acid ismore than 50 mass % and a dipping time is more than 60 seconds, cleaningor etching of the matrix surface is uneven, and hence there is also aprobability that Rku cannot be 5.0 or less.

Second Embodiment: Cu—Fe—P Alloy Sheet with High Strength and ExcellentBendability (r Value)

In the present invention, r value parallel to the rolling direction of aCu—Fe—P alloy sheet should be 0.3 or more, in order to improvebendability of the copper alloy sheet provided with the tensile strengthof 500 MPa or more and the hardness of 150 Hv or more, as stated above.The r value is preferably 0.35 or more and 0.5 or less.

As stated above, in a Cu—Fe—P alloy sheet that is provided with highstrength by increasing an amount of the work-hardening by theheavy-working with an increase in a working ratio in the cold-rolling,the alloy sheet has significant anisotropy of crystal orientation inwhich grain size is significantly elongated in the rolling direction.

As a result, in a Cu—Fe—P alloy sheet after being subjected to thecold-rolling, r value perpendicular to the rolling direction isnecessarily larger than that parallel thereto.

In a Cu—Fe—P alloy sheet according to the present invention, bendingworks thereof are entirely performed in the direction parallel to therolling direction, for the above applications such as lead frames; thatis, Good Way bending (bending axis is perpendicular to the rollingdirection) is performed.

Accordingly, the present invention specifies the r value parallel to therolling direction of a copper alloy sheet, which becomes necessarilysmall, mainly for the purpose of improving the Good way bending. Inother words, when the r value (parallel to the rolling direction of acopper alloy sheet) that becomes necessarily small by performing theafore-mentioned cold-rolling for providing high strength, is made large,the other r value (perpendicular to the rolling direction) that becomesnecessarily large likewise, becomes larger.

For example, when the r value parallel to the rolling direction of acopper alloy sheet is made 0.3 or more, the other r value perpendicularto the rolling direction becomes necessarily larger or equal to roughly0.4.

(Measurement of r Value)

The r value parallel to the rolling direction of a copper alloy sheet isdetermined by a tensile test using a test piece in accordance with JIS5, the test piece being made in a way that the direction parallel to therolling direction of the sheet is the longitudinal direction of the testpiece. A tensile test is conducted at a fixed tension rate of 10 mm/min,after the above JIS 5 test piece is fixed to a tensile tester, and thenan extensometer is fixed thereto, for reproducibility.

The r value is calculated by the following equation, using a verticalmodulus gauge value L (initial value L₀) and a horizontal modulus gaugevalue W (initial value W₀) or the like, in order to calculate from areduction ratio of a sheet thickness to a sheet width of a materialbetween 0 point and 0.5% strain point, as a plastic strain ratio: rvalue=In(W/W₀)/[In(L/L₀)−In(W/W₀)].

(Component Composition of Copper Alloy Sheet)

In the present invention, a copper alloy sheet is required to have thebasic properties for semiconductor lead frames or the like, such as highstrength of which tensile strength is 500 MPa or more and of whichhardness of 150 Hv or more. The copper alloy sheet has excellentplatability by which the unusual precipitation of the plating areprevented, in addition to satisfying these basic properties, or on thepremise that these basic properties are not deteriorated. For thispurpose, the Cu—Fe—P alloy sheet has a basic composition containing: Fe:0.01 to 0.50% and P: 0.01 to 0.15%, with the remainder of Cu andinevitable impurities.

The copper alloy sheet may further selectively contain elements such asZn and Sn, which will be described later, relative to the basiccomposition. It is also acceptable that the copper alloy sheet containselements (impurity elements) other than the described elements, as faras they do not impair the properties of the present invention. It isnoted that all of the contents of alloy elements and impurity elementsare represented by mass %.

(Fe)

Fe is a major element that precipitates as Fe or a Fe-groupintermetallic compound to increase strength and softening resistance ofa copper alloy. When an Fe content is too small, contribution to theincrease in the strength is insufficient, resulting in decreasedstrength even if the final cold-rolling is performed under theheavy-working conditions, while improvement of electric conductivity issatisfied. On the other hand, when an Fe content is too large, electricconductivity is decreased. In addition, because an amount of dispersoidsis large and the dispersoids are starting points for breaks, strengthand softening resistance are adversely deteriorated. Accordingly, an Fecontent should be within the range of 0.01 to 0.50%, preferably 0.15 to0.35%.

(P)

P is a major element serving as forming a compound with Fe to increasestrength of a copper alloy, in addition to having a deoxidizing action.When a P content is too small, precipitation of a compound isinsufficient, and contribution to increase in the strength isinsufficient, resulting in decreased strength even if the finalcold-rolling is performed under the heavy-working conditions, whileimprovement of electric conductivity is satisfied. On the other hand,when a P content is too large, not only electric conductivity but alsohot workability are deteriorated, causing a crack to easily occur.Accordingly, a P content should be within the range of 0.01 to 0.15%,preferably 0.05 to 0.12%.

(Other Elements)

The contents of Zn, Sn, Mn, Mg, Ca, Zr, Ag, Cr, Cd, Be, Ti, Co, Ni, Au,Pt, S, Pb, Hf, Th, Li, Na, K, Sr, Pd, W, Si, Nb, Al, V, Y, Mo, In, Ga,Ge, As, Sb, Bi, Te, B, and misch metal, may be the same as with FirstEmbodiment.

(Production Condition)

Preferable production conditions for making the structure of a copperalloy sheet compatible with the above-described structure specified bythe present invention, will be described below. The copper alloy sheetaccording to the present invention does not require the normalproduction process per se to be changed drastically and can be producedthrough the same process as the normal one, except the preferable finallow-temperature continuous annealing conditions, which will be describedlater.

That is, a copper alloy melt adjusted so as to have the above-describedpreferable component composition is at first cast. An obtained ingot issubjected to facing, and to a heat treatment or a homogenization heattreatment, and then to hot-rolling, followed by cooling with water. Thehot-rolling may be performed under the normal conditions.

Thereafter, primary cold-rolling referred to as intermediate rolling isperformed, followed by annealing and cleaning, and still further byfinish (final) cold-rolling and low-temperature annealing (finalannealing, finish annealing) , such that a copper alloy sheet or thelike having a product sheet thickness is produced. These annealing andcold-rolling may be performed repeatedly. For example, in the case of acopper alloy sheet used in semiconductor materials for lead frames orthe like, a product sheet thickness is about 0.1 to 0.4 mm.

A solution treatment and a quenching treatment by water-cooling of acopper alloy sheet maybe performed before the primary cold-rolling. Atthe time, a solution treatment temperature is selected, for example,within the range of 750 to 1000° C.

(Final Cold-Rolling)

The final cold-rolling is also performed in the normal process. In orderto provide the tensile strength of 500 MPa or more and the hardness of150 Hv or more to a Cu—Fe—P alloy sheet in which the contents of solidsolution strengthening elements are strictly limited, a working-ratio inthe final cold-rolling is determined on the side of the heavy-working ina relation with the working ratio in the cold-rolling so far.

A minimum reduction ratio per one pass (cold-rolling ratio) in the finalcold-rolling is preferably 20% or more. When a minimum reduction ratioper one pass in the final cold-rolling is less than 20%, a compressiveforce occurring in the direction of the sheet width is small, and hencea thickness strain becomes large, causing r value not to be increased.

(Final Annealing)

Conditions of the final low-temperature annealing performed after thefinal cold-rolling have significant influence on the r value parallel tothe rolling direction of a Cu—Fe—P alloy sheet. With respect to thepoint, in the present invention, the r value parallel to rollingdirection of the sheet is controlled so as to be 0.3 or more, as statedabove; and for the purpose, the low-temperature annealing is performedby a continuous annealing, and at the time, an appropriate tensionwithin the range of 0.1 to 8 kgf/mm² is applied to a passing sheet.Thereby, a tension-compression stress with a small change of sheetthickness is provided. The r value of the sheet is increased by theplastic stress.

When the tension is too small, that is, less than 0.1 kgf/mm², a tensionloaded on the sheet is insufficient, and hence the r value parallel tothe rolling direction of a Cu—Fe—P alloy sheet is not larger or equal to0.3, depending on equipment conditions and sheet thickness. On the otherhand, when the tension is too large, that is, more than 8 kgf/mm², apassing sheet having a thin thickness within the afore-mentioned rangeof 0.1 to 0.4 mm, tends to easily break, depending on equipmentconditions and sheet thickness.

The conditions of the final low-temperature continuous annealing havesignificant influence on the basic properties such as strength andelongation or the like, as well as the r value. With respect to thispoint, in the present invention, the final continuous annealingperformed in a continuous heat treatment furnace is preferably performedunder low-temperature conditions, that is, at a temperature of 100 to400° C. for 0.2 minutes or more and 300 minutes or less. In the usualproduction process for producing a copper alloy sheet used for typicallead frames, the final annealing is not performed after the finalcold-rolling, in order to avoid a decrease in strength, except theannealing for relieving a stress (350° C. for about 20 seconds). In thepresent invention, however, a decrease in strength can be suppressed bya lowered temperature in the final annealing. And, bendability or thelike can be improved by the final annealing performed at alow-temperature.

When a continuous annealing temperature is lower than 100° C., or anannealing time is less than 0.2 minutes, or this low-temperatureannealing is not performed, there is a high probability that thestructure and properties of the copper alloy sheet are hardly changedfrom the state after the final cold-rolling. Conversely, when theannealing is performed at an temperature exceeding 400° C., or theannealing is performed for more than 300 minutes, recrystallizationoccurs, rearrangement and recovery phenomena of the dislocation occurexcessively, and precipitates become coarse; therefore, there is a highprobability that the stampability and the strength of the sheet aredecreased.

A line speed during the continuous annealing is preferably controlled soas to be within the range of 10 to 100 m/min. When the line speed is tooslow, recovery and recrystallization of a material progress too much.Accordingly, the strength and the elongation are decreased. However, theline speed is not needed to be faster exceeding 100 m/min, because ofconstraint (capacity limit) of the equipment and of a possibility ofdiscontinuity of sheets in the continuous annealing.

On the other hand, in the batch-type final annealing, tension cannot beapplied to a sheet during annealing, and hence the r value parallel tothe rolling direction of a Cu—Fe—P alloy sheet is not improved. And, thebasic properties such as strength and elongation cannot be obtainedbecause of the same reasons as with the case where a line speed is tooslow in the continuous annealing.

Third Embodiment: Cu—Fe—P Alloy Sheet with High Strength and ExcellentStampability at Stamping Process

Importance of each requirement for satisfying required properties of aCu—Fe—P alloy sheet according to the present invention used forsemiconductor lead frames or the like, and an embodiment of theinvention will be described specifically below.

(Component Composition of Copper Alloy Sheet)

In the present invention, a copper alloy sheet preferably has basicproperties as a material used for semiconductor lead frames or the like,such as the high strength of which tensile strength is 500 MPa or more,and the hardness of 150 Hv or more or the like. The copper alloy sheetaccording to the present invention has excellent stampability inaddition to satisfying these basic properties, or on the premise thatthese basic properties are not deteriorated. For this purpose, theCu—Fe—P alloy sheet has a basic composition containing: Fe: 0.01 to0.50% and P: 0.01 to 0.15%, with the remainder of Cu and inevitableimpurities.

In the present invention, the copper alloy sheet may further selectivelycontain elements such as Zn and Sn, which will be described later,relative to the basic composition. It is also acceptable that the copperalloy sheet contains elements (impurity elements) other than thedescribed elements, as far as they do not impair the properties of thepresent invention. It is noted that all of the contents of alloyelements and impurity elements are represented by mass %.

(Fe)

Fe is a major element that precipitates as Fe or an Fe-groupintermetallic compound to increase strength and softening resistance ofa copper alloy. When an Fe content is too small, precipitation of theabove precipitated particles is small under a certain productioncondition, and hence contribution to an increase in the strength isinsufficient, resulting in decreased strength, while improvement ofelectric conductivity is satisfied. On the other hand, when an Fecontent is too large, electric conductivity and the Ag platability aredeteriorated. In the case, when intending to increase a precipitationamount of the above precipitated particles in order to increase electricconductivity forcedly, it causes the precipitated particles to developand to be coarse. Thereby, the strength and the tensile propertyspecified by the present invention cannot be obtained, resulting indecreased stampability. Accordingly, an Fe content should be within therange of 0.01 to 0.50%, preferably 0.15 to 0.35%.

(P)

P is a major element serving as forming a compound with Fe to increasestrength of a copper alloy, in addition to having a deoxidizing action.When a P content is too small, precipitation of a compound isinsufficient under a certain production condition, and hence desiredstrength cannot be obtained. On the other hand, when a P content is toolarge, not only electric conductivity is decreased but also the tensileproperty specified by the present invention cannot be obtained,resulting in the decreased hot workability and stampability.Accordingly, a P content should be within the range of 0.01 to 0.15%,preferably 0.05 to 0.12%.

(Other Elements)

The contents of Zn, Sn, Mn, Mg, Ca, Zr, Ag, Cr, Cd, Be, Ti, Co, Ni, Au,Pt, S, Pb, Hf, Th, Li, Na, K, Sr, Pd, W, Si, Nb, Al, V, Y, Mo, In, Ga,Ge, As, Sb, Si, Te, B, and misch metal, may be the same as with FirstEmbodiment.

(Tensile Properties of Sheet)

In the present invention, on the premise of the afore-mentionedcomponent composition, tensile properties of a Cu—Fe—P alloy sheet, suchas tensile modulus and ratio of the uniform elongation to the totalelongation, are specified as stated above, and thereby excellentstampability of the alloy sheet can be ensured, wherein the twomeasurements are determined by a tensile test using a test piece takenthe width direction (right-angled direction) of the alloy sheet, whichis perpendicular to the rolling direction of the alloy sheet, as thelongitudinal direction of the test piece.

(Tensile Modulus)

At first, the tensile modulus (Young's modulus) of a Cu—Fe—P alloysheet, which is determined by a tensile test, should be more than 120GPa. The tensile modulus (Young's modulus) is preferably 125 GPa ormore. As the tensile modulus is larger, an accumulated amount of strainsthat are loaded on a sheet when the sheet is stamped, is smaller.Accordingly, a stamping break occurs at an early time during a stampingprocess, and thereby a shear plane ratio is small, leading to theimproved stampability.

On the other hand, when the tensile modulus is small, that is, less thanor equal to 120 GPa, an accumulated amount of strains that are loaded ona sheet during a stamping process, is large. Accordingly, a stampingbreak does not occur during a stamping process, and thereby a shearplane ratio is large, resulting in the deteriorated stampability.

The reasons why the tensile modulus is as low as 120 GPa include,particularly in a Cu—Fe—P alloy sheet, the following major reasons,although other reasons can be also considered: homogenization of thestructure of a sheet is insufficient (the structure of a sheet isinhomogeneous) upon a homogenization heat treatment or a heatingtreatment prior to the hot-rolling, which is described later; atemperature at the start of cooling with water after the hot-rolling, istoo low; or a line speed during the batch-type final annealing or evenduring the continuous final annealing, is slow or the like.

(Uniform Elongation/Total Elongation)

Next, a ratio of the uniform elongation to the total elongation oruniform elongation/total elongation, of a Cu—Fe—P alloy sheet, which isdetermined by a tensile test, should be less than 0.50, preferably lessthan 0.45. As uniform elongation/total elongation is larger, that is,0.50 or more, in other words, as a ratio of the uniform elongation tothe total elongation is larger, the sheet (material) is ductilelydeformed upon stamping. Due to this, a deformation amount up to a breakupon stamping is larger, and hence a shear plane ratio is large,resulting in the decreased stampability. On the other hand, when uniformelongation/total elongation is less than 0.50, a break caused bystamping occurs at an early time upon stamping, and hence a shear planeratio is small, leading to the improved stampability.

The reasons why the uniform elongation/total elongation is as large as0.5 or more include the reasons to be as follows: in a Cu—Fe—P alloysheet, in particular, an amount of precipitates in the sheet structureis insufficient because a temperature at the start of the cooling withwater after the hot-rolling is too high; recovery and recrystallizationof a material progress too much because a temperature of theintermediate annealing is too high; an amount of precipitates in thesheet structure is insufficient because a period of the intermediateannealing is too short; and a line speed during the batch-type finalannealing or even during the continuous final annealing, is slow, or thelike.

(Tensile Test)

A tensile test by which the tensile modulus and a ratio of the uniformelongation to the total elongation specified by the present invention,are determined (measured), are carried out under the following testconditions, for reproducibility. A test piece is one in accordance withJIS 5, which is taken from a Cu—Fe—P alloy sheet thus obtained(produced) in away that the longitudinal direction of the test piece isto be the direction perpendicular to the rolling direction of the alloysheet. A tensile test is conducted at a fixed tension speed of 10mm/min, after the above test piece is fixed to a tensile tester and anextensometer is then fixed thereto. The universal tester 5882 made byInstron is preferable to be used.

Tensile strength is determined from values obtained by measurement usingthe tester, and the total elongation is determined by measuring thedistance between two marks with test pieces butt jointed after testing.Tensile modulus and total elongation are determined from values obtainedby the extensometer.

(Production Processes)

Preferable production conditions for making the structure of a copperalloy sheet compatible with the above-described structure specified bythe present invention, will be described below. As stated above, thetensile modulus and a ratio of the uniform elongation to the totalelongation, which are specified by the present invention, are naturallyaffected greatly by a component composition of a Cu—Fe—P alloy sheet,and also affected greatly by the production processes and the productionconditions; hence, such properties cannot be determined only by acomponent composition. Regarding this point, in order to obtain thetensile properties such as the tensile modulus and a ratio of theuniform elongation to the total elongation that are specified by theinvention as stated above, the production processes and the productionconditions of a Cu—Fe—P alloy sheet such as a homogenization heattreatment, a temperature at the start of cooling with water after thehot-rolling, a temperature of the intermediate annealing, and a linespeed during the final continuous annealing, should be controlled asfollows:

That is, a copper alloy melt adjusted so as to have the above-describedcomponent composition of the present invention is at first cast. Meltingand casting is performed in a normal process such as the continuouscasting and the semi-continuous casting, and it is preferable that acopper melting material with less contents of S and Pb is used in orderto limit contents of S and Pb as stated above. Prior to thehomogenization heat treatment or the heating treatment of the ingot, theingot is subjected to a normal facing.

(Homogenization Heat Treatment or Heating Treatment)

Homogenization of the structure of a sheet is insufficient (thestructure of a sheet is inhomogeneous) upon the homogenization heattreatment or the heating treatment of the ingot prior to thehot-rolling, the structure of a Cu—Fe—P alloy sheet that is finallyobtained is also inhomogeneous, resulting in that not only the strengthis decreased but also the tensile modulus is as low as 120 Gpa.Accordingly, the homogenization heat treatment or the heating treatmentof an ingot is preferably to be performed at a temperature of at least900° C. for 2 hours or more, in accordance with the thickness or thesize of the ingot.

(Hot-Rolling)

The hot-rolling is begun at a temperature of 900° C. or more, and afterthe hot-rolling is finished, cooling with water of the hot-rolled sheetis begun at a temperature of 700° C. to 800° C. When a temperature atthe start of the cooling with water after the hot-rolling is finished,is higher than 800° C., precipitates in the structure are not formed dueto the high temperature at the start of the cooling, resulting in thatan amount of precipitates is insufficient. Thereby, a ratio of theuniform elongation to the total elongation is large, that is, a ratio ofthe uniform elongation to the total elongation is not less than 0.50.

On the other hand, when a temperature at the start of the cooling withwater after the hot-rolling is finished, is less than 700° C., the grainsize is too fine, and not only the tensile modulus is decreased but alsoa ratio of the uniform elongation to the total elongation is too large;therefore, a ratio thereof also is not less than 0.50. In addition, thestrength is decreased due to generation of coarse precipitates.

Subsequently, the primary cold-rolling referred to as the intermediaterolling is performed on the sheet that is cooled with water after thehot-rolling is finished, followed by an annealing and a cleaning.Furthermore, a finish (final) cold-rolling and a final annealing(low-temperature annealing, finish annealing) are performed so that acopper alloy sheet or the like having a product sheet thickness isproduced. These annealing and cold-rolling may be performed repeatedly.For example, when a copper alloy sheet is used for a semiconductormaterial for lead frames or the like, the product sheet thickness isabout 0.1 to 0.4 mm.

(Intermediate Annealing)

In the above processes, the conditions of the intermediate annealingalso affect greatly a ratio of the uniform elongation to the totalelongation. The intermediate annealing in which a ratio of the uniformelongation to the total elongation is less than 0.50, is performed at atemperature of 430° C. or less for 5 hours or more. When a temperatureof the intermediate annealing is too high, not only recovery andrecrystallization of a material progress too much, causing the strengthto be decreased, but also a ratio of the uniform elongation to the totalelongation is too large, resulting in that the ratio is not less than0.50. When a period of the intermediate annealing is too short, anamount of precipitates formed in the structure of a sheet isinsufficient, resulting in decreased electric conductivity.

(Final Annealing)

In the above processes, the conditions of the final annealing greatlyaffect the tensile modulus and a ratio of the uniform elongation to thetotal elongation. In order to obtain such properties of a Cu—Fe—P alloysheet that the tensile modulus exceeds 120 GPa and a ratio of theuniform elongation to the total elongation is less than 0.50, it isneeded that a sheet (coil) is subjected to a continuous annealing inwhich a sheet (coil) continuously passes through a furnace and isprocessed.

In order to obtain such properties, a line speed during the finalannealing is needed to be controlled so as to be within the range of 10to 100 m/min. When the line speed is too slow, recovery andrecrystallization of a material progress too much; hence, not only thestrength is decreased but also a ratio of the uniform elongation to thetotal elongation is too large, that is, the ratio is not less than 0.50.The tensile modulus is also below 120 GPa. However, the line speed isnot needed to be faster exceeding 100 m/min, because of constraint(capacity limit) of the equipment and of a possibility of discontinuityof sheets in the continuous annealing.

On the other hand, in the batch-type final annealing, the tensilemodulus and a ratio of the uniform elongation to the total elongation ina tensile test that are specified by the present invention as statedabove, cannot be obtained, because of the same reason as with the casewhere a line speed is too slow in the continuous annealing.

Fourth Embodiment: Cu—Fe—P Alloy Sheet with High Strength and ExcellentPlatability

Importance of each requirement for satisfying required properties of aCu—Fe—P alloy sheet according to the present invention used forsemiconductor lead frames or the like, and embodiments of the inventionwill be described specifically below.

(Component Composition of Copper Alloy Sheet)

In the present invention, a copper alloy sheet preferably has basicproperties as a material used for semiconductor lead frames or the like,such as the high strength of which tensile strength is 500 MPa or moreand of which hardness is 150 Hv or more or the like. The copper alloysheet according to the present invention has excellent platability bywhich the unusual precipitation of the plating is prevented, in additionto satisfying these basic properties, or on the premise that these basicproperties are not deteriorated. For this purpose, the Cu—Fe—P alloysheet has a basic composition containing: Fe: 0.01 to 0.50% and P: 0.01to 0.15%, with the remainder of Cu and inevitable impurities.

In the present invention, the copper alloy sheet is characterized by acomponent composition in which, relative to the basic composition, C iscontained in an amount of 3 to 15 ppm and contents of O and H areregulated so as to be 40 ppm or less and 0.7 ppm or less, respectively.

The copper alloy sheet may further selectively contain elements such asZn and Sn, which will be described later, relative to the basiccomposition. It is also acceptable that the copper alloy sheet containselements (impurity elements) other than the described elements, as faras they do not impair the properties of the present invention. It isnoted that all of the contents of alloy elements and impurity elementsare represented by mass %.

(Fe)

Fe is a major element that precipitates as Fe or an Fe-groupintermetallic compound to increase strength and softening resistance ofa copper alloy. When an Fe content is too small, precipitation of theabove precipitated particles is small under a certain productioncondition, and hence contribution to an increase in the strength isinsufficient, resulting in decreased strength, while improvement ofelectric conductivity is satisfied. On the other hand, when an Fecontent is too large, electric conductivity is decreased. In the case,when intending to increase a precipitation amount of the aboveprecipitated particles in order to increase electric conductivityforcedly, it causes the precipitated particles to develop and to becoarse, resulting in decreased platability. In addition, strength andsoftening resistance are also deteriorated. Accordingly, an Fe contentshould be within the range of 0.01 to 0.50%, preferably 0.15 to 0.35%.

(P)

P is a major element serving as forming a compound with Fe to increasestrength of a copper alloy, in addition to having a deoxidizing action.When a P content is too small, precipitation of a compound isinsufficient under a certain production condition, and hence desiredstrength cannot be obtained. On the other hand, when a P content is toolarge, not only electric conductivity is decreased but also hotworkability is decreased. Accordingly, a P content should be within therange of 0.01 to 0.15%, preferably 0.05 to 0.12%.

(C)

O and H are inevitably present in a Cu—Fe—P alloy sheet in certaincontents, and they become starting points for inclusions and pores. Oand H tend to agglomerate, and agglomeration thereof makes the formedinclusions and the pores coarse, which are stating points (cause) forthe unusual precipitations of the Ag plating or the like. Inclusions andpores are usually present on the surface of a Cu—Fe—P alloy sheet;however, unless they are particularly coarse, they don't become thestarting points for the above unusual precipitation such as Ag plating,as far as the sizes thereof are normal or fine.

C serves as suppressing agglomeration of O and H that are inevitablypresent in a Cu—Fe—P alloy sheet in certain amounts, and as increasingthe starting points of inclusions and pores, and as making the sizes ofthe formed inclusions and pores normal or fine. Thereby, C prevents theformed inclusions and pores from being particularly coarse in theirsizes, and prevents the inclusions and pores from being the startingpoints for the unusual precipitation of the above Ag plating or thelike.

In order to exhibit the above function of C, it is necessary that C iscontained in an amount of 3 ppm or more. When a C content is less than 3ppm, there is not a significant difference from the C content in which Cis naturally mixed therein; hence, the above function of C that preventsthe unusual precipitation of Ag plating or the like, cannot beexhibited.

On the other hand, when a C content exceeds 15 ppm, more strictly 10ppm, coarse carbides are formed, which adversely become the startingpoints (cause) of the above unusual precipitation of Ag plating or thelike. As stated above, C is easy to disperse, and therefore it is verydifficult that C is contained in an amount exceeding 15 ppm, even whenan Fe—C base alloy is added in a melt stream as is in Patent Document11.

Accordingly, a C content should be within the range of 3 to 15 ppm,preferably 3 to 10 ppm. It is noted that a C content is determined byheating a sample under oxygen atmosphere to extract carbon therein andby analyzing the carbon with a combustion-infrared absorption method, inaccordance with JIS Z2615.

(O, H)

In the present invention, in order to ensure the operation effect of theabove C, contents of O and H, which are starting points for inclusionsand pores, are regulated. Specifically, an O content is regulated so asto be 40 ppm or less, preferably 20 ppm or less; and an H content isregulated so as to be 1.0 ppm or less, more preferably 0.5 ppm or less.When O content and/or H content are too large, the amounts of C and H onwhich C does not act are too large even when C is contained in an amountwithin the above range; and hence O and H agglomerate, causing theformed inclusions and pores to be coarse, which become the startingpoints (cause) of the above unusual precipitation of Ag plating or thelike.

However, the higher limits of the contents of O and H specified by thepresent invention are not particularly lower (smaller) as compared tothose of conventional techniques, nor particularly higher (larger). Inother words, the contents are at normal concentration levels for aCu—Fe—P alloy sheet. That is, the higher limits of the contents of O andH specified by the present invention, conform to the purpose that theabove unusual precipitation of the plating can be prevented, even whenoxygen and hydrogen are contained to some extent in the casting andmelting process of the present invention.

An O content is determined by extracting O in a sample with an inert gasfusion method and by analyzing the O with a combustion-infraredabsorption method, in accordance with JIS 22613. An H content isdetermined by extracting H in a sample with an inert gas fusion methodand by analyzing the H with a thermal conductivity method.

(Other Elements)

The contents of Zn, Sn, Mn, Mg, Ca, Zr, Ag, Cr, Cd, Be, Co, Ni, Au, Pt,S, Pb, Hf, Th, Li, Na, K, Sr, Pd, W, Si, Nb, Al, V, Y, Mo, In, Ga, Ge,As, Sb, Bi, Te, B, and misch metal, may be the same as with FirstEmbodiment.

(Production Processes)

Preferable production conditions for making the structure of a copperalloy sheet compatible with the above-described structure specified bythe present invention, will be described below. The copper alloy sheetaccording to the present invention does not require the normalproduction process per se to be changed drastically and can be producedthrough the same process as the normal one, except the preferableconditions for controlling the above contents of C, H, and O.

A copper alloy melt adjusted so as to have the above-described componentcomposition of the present invention is at first cast. Melting andCasting is performed in a normal process such as continuous casting andsemi-continuous casting. At the time, it is preferable that a coppermelting material with smaller contents of S and Pb is used in order tolimit the contents of the above S and Pb, because S and Pb are to becontained from the copper melting material.

(Control of C Content)

In the melting and casting process of a normal air melting furnace,sources of C solid solution dissolved into a melt are refractories ofthe furnace wall or a carbon composite for shielding air that is mountedon the melt in the air melting furnace, or the like. In a vacuum meltingfurnace, a source of C is refractories of the furnace wall. In thepresent invention, an amount of C dissolved from these sources into amelt can be controlled by controlling a temperature of a copper alloymelt (melting temperature) without using intentional measures for addingC such as addition of Fe—C base material. As control of the temperatureof a copper alloy melt, the temperature thereof in an air meltingfurnace or a vacuum melting furnace is a relatively high temperature of1300° C. or more, while the temperature thereof in the normal meltingprocess is less than about 1200° C. Of course, it is also possible thatthe C content of the present invention is satisfied by combiningintentional measures for adding C such as use of a carbon crucible andaddition of an Fe—C base material or the like, with the above control ofthe temperature of a copper alloy melt.

An amount of C (C content) dissolved from the above sources of C solidsolution into a melt, is increased by raising the temperature of acopper alloy melt to such a high temperature, and thereby the C contentspecified by the present invention is satisfied. When the temperature ofa copper alloy melt is less than 1300° C., an amount of the dissolved Cis insufficient as is the case with a normal process; hence, an amountof C in the final Cu—Fe—P alloy sheet is less than 3 ppm. In the casesof an air melting furnace and a vacuum melting furnace, when an averagecooling rate (solidification rate) from the start of casting to 600° C.is slow, C in the melt is likely to disperse halfway; hence, the averagecooling rate is preferably to be as great as more than 5.0° C/s .

(Control of Contents of O and H)

In order to suppress increase in contents of O and H, it is important tosuppress contact between a copper melt and air as few as possible, inthe melting and casting process. For example, in the cases of a vacuummelting furnace (source of C solid solution is refractories of thefurnace wall) and an air melting furnace, the average cooling rate(solidification rate) from the start of casting to 600° C. should be5.0° C/s. As stated above, the average cooling rate is also effectivefor controlling a C content . Control of the atmosphere of an annealingfurnace in the subsequent process is also effective for loweringcontents of O and H.

Thereafter, an obtained ingot is subjected to facing, and to a heattreatment or a homogenization heat treatment, and then to hot-rolling,followed by cooling with water. Further, primary cold-rolling referredto as intermediate rolling is performed, followed by annealing andcleaning, and still further by finish(final)cold-rolling andlow-temperature annealing (final annealing, finish annealing), such thata copper alloy sheet or the like having a product sheet thickness isproduced. These annealing and cold-rolling may be performed repeatedly.For example, in the case of a copper alloy sheet used in semiconductormaterials for lead frames or the like, a product sheet thickness isabout 0.1 to 0.4 mm.

A solution treatment and a quenching treatment by water-cooling of acopper alloy sheet maybe performed before the primary cold-rolling. Atthe time, a solution treatment temperature is selected, for example,within the range of 750 to 1000° C. A sheet that has been subjected tothe final cold-rolling may be a final product sheet as it is, or may besubjected to the low-temperature annealing for relieving a strain.

EXAMPLES Example 1

An example of the present invention will be described below. Cu—Fe—Palloy sheets having each component composition illustrated in Table 1were respectively produced, with only the conditions of a cleaningtreatment entailing chemical etching after the final annealing process,being changed variously as illustrated in Table 2. The resistance ofpeel off (peeling-off temperature) of an oxidation film formed on eachcopper alloy sheet was evaluated, results of which are shown in Table 2.

Specifically, copper alloys having each component compositionillustrated in Table 1 were respectively melted in a coreless furnace,and thereafter ingots with their sizes of 70 mm in thickness×200 mm inwidth×500 mm in length were produced in the semi-continuous castingprocess. After the surface of each ingot was subjected to facing and aheat treatment, sheets with a thickness of 16 mm were prepared by beingsubjected to the hot-rolling at a temperature of 950° C., which werequenched in water from a temperature of 750° C. or more . The oxidizedscale was removed, and thereafter the primary cold-rolling (intermediaterolling) was performed. The resulting sheet was subjected to facing, andthereafter the final cold-rolling was performed in which 4 passes of thecold-rolling were performed with the intermediate annealingtherebetween. Subsequently, the final continuous annealing was performedunder the low-temperature conditions of 350° C. for 20 seconds, suchthat a copper alloy sheet with a thickness of 0.15 mm that correspondsto the thinning of lead frames, was obtained.

In the final cold-rolling, a bright roll (surface polished roll) wasused in common among each sheet, in which: a minimum reduction ratio perone pass is 30%; a centerline average roughness Ra of the surface of theroll is 0.2 μm or less; and a maximum height Rmax thereof is 1.5 μm orless.

After the final continuous annealing, the Cu—Fe—P alloy sheet wassubjected to a cleaning treatment entailing chemical etching in whichthe sheet was dipped in an aqueous sulfuric acid solution (roomtemperature) under the conditions illustrated in Table 2, and therebyRku of the surface of the sheet was controlled.

In each copper alloy illustrated in Table 1, the remaining element otherthan the described elements is Cu, and as other impurity elements, atotal content of Hf, Th, Li, Na, K, Sr, Pd, W, S, Si, C, Nb, Al, V, Y,Mo, Pb, In, Ga, Ge, As, Sb, Bi, Te, B, and misch metal was less than 0.1mass %.

In the case where one or more elements selected from Mn, Mg, and Ca werecontained, a total content thereof was to be within the range of 0.0001to 1.0 mass %; and in the case where one or more elements selected fromZr, Ag, Cr, Cd, Be, Ti, Co, Au, and Pt were contained, a total contentthereof was to be within the range of 0.001 to 1.0 mass %; and further atotal content of these whole elements was to be 1.0 mass % or less.

In each example, a sample was taken from each copper alloy sheet thusobtained, such that the properties such as tensile strength, hardness,and electric conductivity; and a centerline average roughness Ra, amaximum height Rmax, and Kurtosis (degree of peakedness) of theroughness curve, in measurement of surface roughness in accordance withJIS B0601, were measured. These results are illustrated in Table 2,respectively.

(Measurement of Surface Roughness)

A centerline average roughness Ra (μm), a maximum height Rmax (μm) , andKurtosis (degree of peakedness) of roughness curve, of the surface ofthe test piece of the obtained copper alloy sheet, were measured byusing a surface roughness tester made by TOKYO SEIMITSU CO., LTD(Product : SURFCOM 1400D) in accordance with JIS B0601. Measurementswere conducted for each 4.0 mm in length at 3 arbitrarily selectedpoints (three places) in the test piece, results of which were averaged.

(Measurement of Hardness)

A test piece with a size of 10×10 mm was taken from each copper alloysheet thus obtained. Hardness of the test piece was measured at 4 pointsof the test piece, with a micro Vickers hardness tester made byMATSUZAWA CO., LTD (Product: “Micro Vickers Hardness Tester”) byapplying a load of 0.5 kg, and an average value thereof was taken as thehardness of the test piece.

(Measurement of Electric Conductivity)

After the copper alloy sheet sample was processed into a slip-shapedtest piece with a size of 10 mm in width×300 mm in length by milling andan electric resistance thereof was measured with a double bridgeresistance meter, the electric conductivity thereof was calculated by anaverage cross-sectional area method.

(Resistance of Peel Off of Oxidation Film)

The resistance of peel off of an oxidation film of each test piece wasevaluated by a critical temperature at which the oxidation film ispeeled off, in a tape peeling test. The tape peeling test was conductedas follows: a test piece with a size of 10×30 mm was cut out from thecopper alloy sheet thus obtained; the test piece was heated at a certaintemperature for 5 minutes in the air; and a commercially available tape(Product: Mending Tape made by Sumitomo 3M Limited) was applied to thesurface of the test piece where an oxidation film was generated, thenthe tape was peeled off. When a heating temperature was increased atintervals of 10° C., the lowest temperature at which the oxidation filmwas peeled off was determined to be a peeling temperature of theoxidation film.

When the peeling temperature of an oxidation film is equal to or higherthan 350° C., it can be said that the resistance of peel off of theoxidation film is sufficient for an increased temperature of heating inthe heating process for producing copper alloy sheets and lead frames.

The above heating for 5 minutes in the air specified by the presentinvention is relatively long, and therefore it can be said that the testcondition for evaluating the resistance of peel off of oxidation film ismore strict than the test condition in which heating is conducted at atemperature of 200 to 500° C. for a relatively shorter time of 3minutes, as described in Patent Documents 2 and 3. In other words, thetest of resistance of peel off of oxidation film according to thepresent invention in which heating is conducted for a relatively longertime, is associated with the resistance of peel off of oxidation film atan increased temperature of the heating in the heating process forproducing copper alloy sheets and lead frames.

On the other hand, it can be said that the test conditions forevaluating resistance of peel off of oxidation film in which heating isconducted for a relatively shorter time of 3 minutes, as is disclosed inPatent Documents 2 and 3, is insufficient to be associated with theresistance of peel off of oxidation film at an increased temperature ofheating in the heating process for producing copper alloy sheets andlead frames. That is, even if good results are obtained from the testconditions for evaluating resistance of peel off of oxidation filmaccording to Patent Documents 2 and 3, the resistance of peel off ofoxidation film at an increased temperature of heating in the heatingprocess for producing copper alloy sheets and lead frames, is not alwaysgood.

As is clear from Tables 1 and 2, each of Inventive Examples 1 to 13 thatare copper alloys having component compositions within the rangespecified by the present invention, has high strength with tensilestrength of 500 MPa or more and hardness of 150 Hv or more. In addition,the centerline average roughness Ra of each copper alloy sheet inmeasurement of the surface roughness in accordance with JIS B0601, is0.2 μm or less, and the maximum height Rmax thereof is 1.5 μm or less.

Furthermore, Inventive Examples 1 to 13 are subjected to a cleaningtreatment by an aqueous sulfuric acid solution under a preferablecondition after the final continuous annealing; hence, each Kurtosis(degree peakedness) of roughness curve thereof is 5.0 or less. As aresult, each of them is provided with the excellent resistance of peeloff of oxidation film in which a peeling temperature of oxidation filmis 350° C. or more. Accordingly, each of Inventive Examples 1 to 13 hasa high adhesion property between the resin and the die pad as asemiconductor base material in assembling semiconductor packages,leading to packages with high reliability.

On the other hand, Comparative Examples 14 and 15 are not subjected to acleaning treatment by an aqueous sulfuric acid solution under apreferable condition after the final continuous annealing. ComparativeExample 16 is too low in the concentration of the sulfuric acid used inthe cleaning treatment by the aqueous sulfuric acid solution.Comparative Example 17 is too high in the concentration of the sulfuricacid used in the cleaning treatment by the aqueous sulfuric acidsolution. Comparative Example 18 is too long in the dipping time in thecleaning treatment by the aqueous sulfuric acid solution. As results ofthese problems, each of Comparative Examples 14 to 18 has Kurtosis(degree of peakedness) of roughness curve exceeding 5.0.

On the other hand, Comparative Examples 14 to 18 are copper alloyshaving component compositions within the range specified by the presentinvention. Each of them has high strength with tensile strength of 500MPa or more and the hardness of 150 HV or more, and the centerlineaverage roughness Ra in measurement of the surface roughness is 0.2 μmor less, and the maximum height Ra is 1.5 μm or less. Nevertheless,because each of Comparative Examples 14 to 18 has Kurtosis (degree ofpeakedness) of roughness curve exceeding 5.0, a peeling temperature ofoxidation film is less than 350° C., resulting in the decreasedresistance peel off of oxidation film. Accordingly, each of ComparativeExamples 14 to 18 has a poor adhesion property between the resin and thedie pad as a semiconductor base material in assembling semiconductorpackages, resulting in packages with low reliability.

Each of Comparative Examples 19 to 22 is subjected to a cleaningtreatment by an aqueous sulfuric acid solution under a preferablecondition after the final continuous annealing; hence each Kurtosis(degree peakedness) of roughness curve thereof is 5.0 or less. As aresult, each of them is provided with the excellent resistance of peeloff of oxidation film.

Nevertheless, an Fe content of Comparative Example 19 is out of thelower limit of 0.01%, and therefore Comparative Example 19 has too poorstrength enough to be used as a semiconductor base material.

An Fe content of Comparative Example 20 is out of the higher limit of5.0%; and therefore comparative example 20 has a remarkably decreasedelectric conductivity, and cannot be used as a semiconductor basematerial.

A P content of Comparative Example 21 is out of the lower limit of0.01%, and therefore Comparative Example 21 has too poor strength enoughto be used as a semiconductor base material.

A P content of Comparative Example 22 is out of the higher limit of0.15%, and a crack occurred during the hot-rolling, and therefore trialproduction was stopped at the time.

From the above results, the critical importance of the componentcomposition and the surface roughness of a copper alloy sheet of thepresent invention, which are for having excellent resistance of peel offof oxidation film in addition to high strength, can be supported; andthe importance of the preferred production conditions for obtaining thesurface roughness can also be supported.

TABLE 1 Component composition of copper alloy sheet Classifi-(Remainder: Cu and impurities) cation No. Fe P Sn Zn Others Inven- 10.28 0.12 0.11 0.31 — tive 2 0.28 0.12 0.11 0.31 — example 3 0.28 0.120.11 0.31 — 4 0.030 0.010 0.10 0.29 — 5 0.49 0.14 0.11 0.30 — 6 0.290.11 — — — 7 0.27 0.10  0.005 — — 8 0.28 0.11 —  0.005 — 9 0.25 0.0845.0  — Mg: 0.005 10 0.26 0.086 — 3.0  Co: 0.10 11 0.26 0.085  0.020 0.25Mn: 0.003, Ni: 0.025 12 0.27 0.084  0.022 0.26 Ca: 0.002, S: 0.003 130.26 0.085  0.019 0.25 Zr: 0.020, B: 0.005 Compar- 14 0.28 0.12 0.780.28 — ative 15 0.49 0.14 0.11 0.30 — example 16 0.28 0.12 0.11 0.31 —17 0.28 0.12 0.11 0.31 — 18 0.28 0.12 0.11 0.31 — 19 0.004 0.01 0.100.30 — 20 0.60 0.14 0.11 0.32 — 21 0.02 0.004 0.10 0.31 — 22 0.48 0.160.12 0.33 — ′ Representations of each element content. “—” representsbelow minimum detectable quantity

TABLE 2 Surface properties of Properties of copper alloy sheet Cleaningtreatment copper alloy sheet Peeling Concentration Rku Tens

e Hard- Electric temperature of of sulfuric Dipping Ra Rmax Degree o

strength ness conductivity oxidation film Classification No. acid timeμm μm peakedness MPa Hv

IACS ° C. Inventive 1 20 10 0.068 0.43 2.6 580 175 75 400 example 2  510 0.050 0.53 4.8 580 175 75 350 3 50 10 0.070 0.51 4.7 580 175 75 350 420 10 0.045 0.42 2.5 520 155 88 400 5 20 10 0.067 0.45 2.7 595 180 73400 6 20 10 0.049 0.42 2.6 540 160 85 400 7 20 10 0.076 0.45 3.0 565 17080 390 8 20 10 0.050 0.40 2.5 550 165 83 400 9 10 40 0.071 0.48 3.9 770235 32 370 10 20 30 0.043 0.41 2.2 630 195 67 410 11 30 10 0.048 0.433.1 565 170 78 390 12 30 20 0.073 0.47 3.4 600 180 71 380 13 40  5 0.0700.52 4.3 570 170 77 360 Comparative 14 —

0.044 0.64 7.3 670 205 53 290 example 15 — — 0.056 0.63 7.4 595 180 73290 16  3 10 0.050 0.55 5.3 580 175 75 330 17 60 10 0.048 0.60 5.6 580175 75 320 18 20 80 0.072 0.59 5.7 580 175 75 320 19 20 10 0.055 0.442.6 470 135 91 400 20 20 10 0.068 0.47 2.9 555 165 67 390 21 20 10 0.0770.43 2.5 495 145 90 400 22 — — — — — — —

—

indicates data missing or illegible when filed

Example 2

An example of the present invention will be described below. Cu—Fe—Palloy thin sheets having component composition illustrated in Table 3were produced with only the tension condition during the finallow-temperature annealing being changed variously, as illustrated inTable 4. In each copper alloy thin sheet, the r value parallel to therolling direction of the thin sheet and the bendability thereof wereevaluated. These results are illustrated in Table 4.

Specifically, copper alloys having each component compositionillustrated in Table 3 were respectively melted in a coreless furnace,and thereafter ingots with their sizes of 70 mm in thickness ×200 mm inwidth×500 mm in length were produced in the semi-continuous castingprocess. After the surface of each ingot was subjected to facing and aheat treatment, sheets with a thickness of 16 mm were prepared by beingsubjected to the hot-rolling, which were quenched in water from atemperature of 650° C. or more. The oxidized scale was removed, andthereafter the primary cold-rolling (intermediate rolling) wasperformed. The resulting sheet was subjected to facing and thecold-rolling with the intermediate annealing therebetween, andthereafter subjected to the final low-temperature annealing at atemperature of 400° C., allowing a copper alloy sheet with a thicknessof 0.15 mm to be obtained, the sheet corresponding to the thinning oflead frames.

The minimum reduction ratio per one pass in the final cold-rolling, andthe tension applied to the sheet during the final low-temperatureannealing, are illustrated in Table 4. The r values of the copper alloythin sheets, which are parallel to the rolling direction of the sheet,were controlled by changing variously only the reduction ratio per onepass in the final cold-rolling and the tension during the finallow-temperature annealing.

In each copper alloy sheet illustrated in Table 3, the remaining elementother than the described elements is Cu, and as other impurity elements,a total content of Hf, Th, Li, Na, K, Sr, Pd, W, S, Si, C, Nb, Al, V, Y,Mo, Pb, In, Ga, Ge, As, Sb, Bi, Te, B, and misch metal was less than 0.1mass %.

In the case where one or more elements selected from Mn, Mg, and Ca werecontained, a total content thereof was to be within the range of 0.0001to 1.0 mass %; and in the case where one or more elements selected fromZr, Ag, Cr, Cd, Be, Ti, Co, Au, and Pt were contained, a total contentthereof was to be within the range of 0.001 to 1.0 mass %; and further atotal content of these whole elements was to be 1.0 mass % or less.

In each example, a sample was taken from each copper alloy sheet thusobtained, such that tensile tests, measurement of electric conductivity,and flexural tests were conducted. These results are also illustrated inTable 4.

(Tensile Test)

In the tensile tests, tensile strength, 0.2 proof stress, and r value,were measured by using the universal tester 5882 made by Instron, underthe afore-mentioned conditions for measuring the r value, that is, at afixed tension speed of 10.0 mm/min, GL of 50 mm, and at roomtemperature.

(Measurement of Electric Conductivity)

After the copper alloy sheet sample was processed into a slip-shapedtest piece with a size of 10 mm in width×300 mm in length by milling andan electric resistance thereof was measured with a double bridgeresistance meter, the electric conductivity thereof was calculated by anaverage cross-sectional area method.

(Test for Evaluating Bendability)

Flexural tests of the copper alloy sheet samples were conducted inaccordance with the technical standard set by the Japan Copper and BrassAssociation. Sheet samples with 10 mm in width×30 mm in length weretaken out, and occurrence of a crack in the bending portion was observedby an optical microscope with 50× magnification, while performing theGood Way bending (bending axis is perpendicular to the rollingdirection) on the sheet sample. Thereby, a ratio R/t of the minimumbending radius R at which a crack does not occur, to the thickness t(0.15 mm) was determined. As R/t is smaller, the bendability is better.However, as a sheet has high strength, the bendability thereof isnecessarily decreased; hence, it is needed that a copper alloy sheetused in semiconductor materials for lead frames or the like, has R/t ofless than 1.5 in the case where the hardness is within the range of 150to 200 Hv, and has R/t of less than 2.0 in the case where the hardnessis 200 Hv or more. In the case where the hardness is less than 150 Hv,which is too low and out of the range specified by the presentinvention, R/t is needed to be less than 0.5.

As is clear from Tables 3 and 4, each of Inventive Examples 31 to 43that are copper alloys having component composition within the rangespecified by the present invention, has high strength with tensilestrength of 500 MPa or more and hardness of 150 Hv or more. Furthermore,each r value thereof parallel to the rolling direction is 0.3 or moredue to the preferable tension applied to the sheets during the finalcontinuous annealing. Accordingly, Inventive Examples 31 to 43 areexcellent in the bendability as semiconductor base materials.

On the other hand, in Comparative Examples 44 and 45, tension was notapplied to the sheets during the final continuous annealing.Consequently, although Comparative Examples 44 and 45 have high strengthin which the tensile strength is 500 MPa or more and the hardness is 150Hv or more, which are specified by the present invention, r valuesparallel to the rolling direction of the sheets are less than 0.3.Accordingly, Comparative Examples 44 and 45 have poor bendability assemiconductor base materials.

An Fe content of Comparative Example 46 is out of the lower limit of0.01%, and therefore Comparative example 46 has too poor strength enoughto be used as a semiconductor base material, while having r valueparallel to the rolling direction of the sheet of 0.3 or more.

An Fe content of Comparative Example 47 is out of the higher limit of5.0%, and therefore Comparative Example 47 has poor bendability for thestrength. In addition, the electric conductivity is remarkably low forthe strength as compared to the same strength level of InventiveExamples, and hence cannot be used as a semiconductor.

A P content of Comparative Example 48 is out of the lower limit of0.01%, and therefore cannot be used as a semiconductor base materialregarding this point, while the r value parallel to the rollingdirection of the sheet is 0.3 or more.

A P content of Comparative Example 49 is out of the higher limit of0.15%, and a crack occurred during the hot-rolling, and therefore trialproduction was stopped at the time.

In Comparative Example 50, the minimum reduction ratio per one pass inthe final cold-rolling is less than 20%. Therefore, the r value parallelto the rolling direction of the sheet is less than 0.3, while the sheethas a component composition within the range specified by the presentinvention, and therefore Comparative Example 50 has poor bendability.

From the above results, the critical importance of the componentcomposition and the r value of a copper alloy sheet of the presentinvention, which are for having excellent bendability in addition tohigh strength, can be supported; and the importance of the preferredproduction conditions for obtaining the r value and the high strengthcan also be supported.

TABLE 3 Component composition of copper alloy sheet Classifi-(Remainder: Cu and impurities) cation No Fe P Sn Zn Others Inven- 310.17 0.056 0.022 0.030 — tive 32 0.16 0.056 0.63 0.058 — example 330.030 0.010 — — — 34 0.49 0.14 — — — 35 0.17 0.059 0.005 — — 36 0.100.034 5.0 — — 37 0.17 0.060 0 0.005 — 38 0.15 0.051 0 3.0  — 39 0.180.058 0.020 0.028 Mn: 0.003 40 0.17 0.060 0.024 0.030 Cr: 0.005 41 0.170.057 0.022 0.033 Ca: 0.001, Ti: 0.010 42 0.18 0.060 0.025 0.025 Mg:0.050, Al: 0.003 43 0.25 0.080 — — Ni: 0.10, Si: 0.002 Compar- 44 0.170.056 0.022 0.030 — ative 45 0.16 0.056 0.63 0.058 — example 46 0.0040.010 — — — 47 0.60 0.14 — — — 48 0.020 0.004 — — — 49 0.48 0.16 — — —50 0.17 0.056 0.022 0.030 — ′ Representations of each element content,“—” represents below minimum detectable quantity

TABLE 4 Minimum Tension during reduction final low- Properties of copperalloy sheet ratio in temperature Bend- final cold- continuous Te

s

e Hard- Electric ability rolling annealing strength ness conductivity

Classification No. % kgf/mm² MPa Hv % IACS value R/t Inventive 31 25 3560 165 83 0.38 1.00 example 32 30 4 665 205 58 0.43 1.33 33 30 3 505150 90 0.40 0.67 34 25 2 590 175 78 0.36 1.33 35 30 3 545 160 85 0.381.00 36 30 3 750 230 35 0.41 1.67 37 20 6 535 160 86 0.43 0.83 38 30 3620 190 70 0.40 1.33 39 30 1 575 170 80 0.36 1.00 40 30 2 565 165 810.37 1.00 41 30 0.5 555 165 82 0.34 1.00 42 30 3 590 175 77 0.39 1.33 4330 3 580 170 79 0.40 1.00 Comparative 44 25 0 550 160 84 0.28 2.00example 45 20 0 650 200 59 0.27 2.67 46 25 1 460 130 90 0.32 0.67 47 201 540 160 68 0.35 2.00 48 20 2 485 140 91 0.34 0.67 49 — — — — — — — 5015 1 555 165 83 0.28 2.00

indicates data missing or illegible when filed

Example 3

An example of the present invention will be described below. Cu—Fe—Palloy sheets were produced in which homogenization heat treatments,temperatures at the start of cooling with water after the hot-rolling,temperatures of the intermediate annealing, and line speeds during thefinal continuous annealing or the like were variously changed. In eachcopper alloy sheet, the tensile properties such as the tensile modulusand the ratio of the uniform elongation to the total elongation, or thetensile strength, the hardness, the electric conductivity, and the shearplane ratio surface or the like, were evaluated. These results areillustrated in Table 5.

Specifically, copper alloys having each component compositionillustrated in Table 5 were respectively melted in a coreless furnace oran air melting furnace, and thereafter ingots with their sizes of 70 mmin thickness×200 mm in width×500 mm in length were produced thesemi-continuous casting process.

After the surface of each ingot was subjected to facing and ahomogenization heat treatment under the conditions (temperature×period)illustrated in Table 6, sheets with a thickness of 16 mm were preparedby being subjected to the hot-rolling at a temperature of 950° C., whichwere quenched in water from the starting temperatures illustrated inTable 6. The oxidized scale was removed, and thereafter the primarycold-rolling (intermediate rolling) was performed. The resulting sheetwas subjected to facing, and thereafter the final cold-rolling wasperformed in which 4 passes of the cold-rolling were performed with theintermediate annealing therebetween, the intermediate annealing beingperformed for 10 hours at the temperatures illustrated in Table 6.Thereby, a copper alloy sheet with a thickness of 0.15 mm thatcorresponds to the thinning of lead frames, was obtained. The copperalloy sheets were subjected to the final annealing in the continuousannealing under the conditions in which a temperature was 350° C. andline speed are illustrated in Table 6, and thereby product copper alloysheets were obtained.

In each copper alloy illustrated in Table 5, the remaining element otherthan the described elements is Cu, and as other impurity elements, atotal content of Hf, Th, Li, Na, K, Sr, Pd, W, Si, Nb, Al, V, Y, Mo, In,Ga, Ge, As, Sb, Bi, Te, B, and misch metal was less than 0.1 mass %.

In the case where one or more elements selected from Mn, Mg, and Ca werecontained, a total content thereof was to be within the range of 0.0001to 1.0 mass %; and in the case where one or more elements selected fromZr, Ag, Cr, Cd, Be, Ti, Co, Ni, Au, and Pt were contained, a totalcontent thereof was to be within the range of 0.001 to 1.0 mass %; andfurther a total content of these whole elements was to be 1.0 mass % orless.

In each example, a test piece (sample) was taken from each copper alloysheet thus obtained in a way that the longitudinal direction of the testpiece was to be the width direction of the alloy sheet, which wasperpendicular to the rolling direction of the alloy sheet; andthereafter the properties such as tensile modulus, ratio of the uniformelongation to the total elongation, tensile strength, hardness, electricconductivity, and shear plane ratio or the like, were evaluated. Theseresults are illustrated in Table 6.

(Measurement of Shear Plane Ratio)

The stampability of a copper alloy sheet is evaluated by a shear planeratio of a lead cross section formed by the press stamping thatsimulates the lead stamping of a copper alloy sheet. When the shearplane ratio is 75% or less, the stampability can be evaluated as good.The evaluation method by the shear plane ratio can evaluate the demandedstampability more properly than that of the press stampability in whicha lead is stamped through a copper alloy sheet and a burr heightoccurring at the time is measured.

In the press stamping tests, leads one of which has a size of 1 mm inwidth×10 mm in length, which is illustrated in FIG. 2, are sequentiallystamped through a copper alloy sheet (test piece) 1 by using a stampingpress (clearance: 5%) and a lubricating oil G-6316 made by NIHONKOHSAKUYU CO., LTD, as stamped holes 2 in which the width direction ofthe alloy sheet, which is perpendicular to the rolling direction of thealloy sheet, is to be the longitudinal direction of the test piece.

Subsequently, the stamped hole 2 was cut at its center along thelongitudinal direction thereof (cut portion is represented by the dotline 3) , and then a shear plane in the stamped hole 2 was determined byobserving the cut cross section of the hole from the arrow 4 direction,and by image analysis of a surface picture of the cut cross sectiontaken by an optical microscope. A shear ratio is specified by a ratio ofthe shear plane area (shear plane area/cut cross sectional area) ,wherein the cut cross sectional area was obtained by multiplying thethickness of the copper alloy sheet 0.15 mm by the measurement width 0.5mm, and the shear plane area was to be a shear plane area within therange of the measurement width 0.5 mm. Three holes were stamped out perone sample and three measurements at 3 points were carried out for eachhole (total 9 points), thereafter a mean value thereof was calculated.

(Measurement of Hardness)

Hardness of the copper alloy sheet sample was measured at 3 points thatare arbitrarily selected, with a micro Vickers hardness tester byapplying a load of 0.5 kg, and an average value thereof was taken as thehardness of the sample.

(Measurement of Electric Conductivity)

After the copper alloy sheet sample was processed into a slip-shapedtest piece with a size of 10 mm in width×300 mm in length by milling andan electric resistance thereof was measured with a double bridgeresistance meter, the electric conductivity thereof was calculated by anaverage cross-sectional area method.

As is clear from Tables 5 and 6, each of Inventive Examples 51 to 61within the range specified by the present invention, has a componentcomposition within the range specified by the present invention. And,each of Inventive Examples 51 to 61 was produced under the productionconditions in which a homogenization heat treatment, a temperature atthe start of cooling with water after the hot-rolling, a line speedduring the final continuous annealing or the like, were within thepreferable ranges. Accordingly, each of Inventive Examples 51 to 61 hasthe tensile modulus more than 120 GPa and the ratio of the uniformelongation/total elongation of less than 0.5.

As a result, each of Inventive Examples 51 to 61 has a relatively highelectric conductivity for the high strength in which the tensile modulusis 500 MPa or more and the hardness is 150 Hv or more; and the shearplane ratio is 75% or less. Moreover, each of them is excellent in thestampability.

However, Inventive Example 53 an Fe content of which is close to thelower limit, and Inventive Example 55 a P content of which is close tothe lower limit, have the relatively lower strength as compared to thoseof other Inventive Examples 51 and 52 or the like. Inventive Example 54an Fe content of which is close to the higher limit, and InventiveExample 56 a P content of which is close to the higher limit, have therelatively larger shear plane ratio and relatively smaller electricconductivity as compared to Inventive Examples 51 and 52.

On the other hand, each of Comparative Examples 62 to 67 was producedunder the production conditions in which a homogenization heattreatment, a temperature at the start of cooling with water after thehot-rolling, a line speed during the final continuous annealing or thelike, were out of the preferable ranges. Accordingly, each ofComparative Examples 62 to 67 has the low tensile modulus of 120 GPa orless, or the ratio of the uniform elongation/total elongation of 0.5 ormore. As a result, each of Comparative Examples 62 to 67 has the shearplane ratio of more than 75%, and therefore has the remarkablydeteriorated stampability.

In Comparative Example 62, the period of the homogenization heattreatment is too short. In Comparative Example 63, the temperatureduring the homogenization heat treatment is too low. In Comparative

Example 64, the temperature at the start of cooling with water after thehot-rolling is too high. In Comparative Example 65, the temperature atthe start of the cooling with water after the hot-rolling is too low. InComparative Example 66, the temperature at the intermediate annealing istoo high. In Comparative Example 67, the line speed during the finalcontinuous annealing is too slow.

The component composition of each of Comparative Examples 68 to 71 isout of the range specified by the present invention, while each of themwas produced in the preferable production conditions. Accordingly, eachof Comparative Examples 68 to 71 has the low tensile modulus of 120 GPaor less, and the ratio of the uniform elongation/total elongation of 0.5or more. As a result, each of Comparative Examples 68 to 71 has theshear plane ratio of more than 75%, and therefore has the remarkablydeteriorated stampability.

In Comparative Example 68, an Fe content is out of the lower limit of0.01%. Therefore, Comparative Example 68 has the high shear plane ratio,and therefore has the deteriorated stampability and the insufficientstrength.

In Comparative Example 69, an Fe content is out of the higher limit of5.0%. Therefore, Comparative Example 68 has the high shear plane ratio,and therefore has the deteriorated stampability and the insufficientstrength.

In the copper alloy of Comparative Example 70, a P content is out of thelower limit of 0.01%. Therefore, Comparative Example 70 has the highshear plane ratio, and therefore has the deteriorated stampability andthe insufficient strength.

In the copper alloy of Comparative Example 71, a P content is out of thehigher limit of 0.15%. Therefore, a crack occurred during thehot-rolling.

From the above results, the critical importance of the componentcomposition of a copper alloy sheet of the present invention, and thetensile properties thereof such as tensile modulus and uniformelongation/total elongation, which provide the excellent stampability inaddition to the high strength, can be supported; and the importance ofthe preferred production conditions for obtaining such tensileproperties can also be supported.

TABLE 5 Component composition of copper alloy sheet Classifi-(Remainder: Cu and impurities) cation No. Fe P Zn Sn Others Inven- 510.17 0.061 0.070 0.035 — tive 52 0.17 0.056 0.062 1.0 — example 53 0.030.060 — — — 54 0.47 0.060 — — — 55 0.32 0.030 — — — 56 0.32 0.13 — — —57 0.17 0.060 0.058 0.56 Ni: 0.005 58 0.17 0.061 0.60 0.10 Mn: 0.01, Ca:0.003 59 0.17 0.060 0.085 0.020 Ni: 0.01, Mn: 0.005, Al: 0.005 60 0.170.061 0.10 0.035 Ti: 0.005, Ca: 0.01 61 0.17 0.058 0.096 0.020 Mg: 0.01,Si: 0.005 Compar- 62 0.15 0.050 0.070 0.030 — ative 63 0.15 0.050 0.0700.025 — example 64 0.17 0.061 0.070 0.035 — 65 0.17 0.061 0.070 0.035 —66 0.17 0.061 0.070 0.035 — 67 0.17 0.061 0.070 0.035 — 68 0.006 0.0580.065 0.020 — 69 0.55 0.061 0.065 0.020 — 70 0.17 0.007 0.10 0.024 — 710.17 0.17 0.10 0.025 — ′ Representations of each element content, “—”represents below minimum detectable quantity

TABLE 6 Production conditions for producing copper alloy sheetsHomogenization Temperature at Line Tensile properties Properties ofcopper alloy sheet heating condi- the start o

Temperature at speed Uniform Shear tions prior cooling

 water intermediate dur

g

l elongatio

Tens

e Hard- Electric plane to hot-rolling afte

 hot-ro

g annealing annealing Mo

lus total strength ness conductivity ratio Classification No. ° C. × h °C. ° C. m/min GPa elongation MPa Hv

IACS

Inventive 51 950° C. × 4 h 780 400 50 128 0.28 560 165 82 73 example 52950° C. × 4 h 750 380 50 146 0.16 670 205 52 65 53 920° C. × 4 h 720 42030 122 0.45 510 150 88 75 54 950° C. × 4 h 750 400 50 124 0.20 600 18074 70 55 950° C. × 4 h 750 400 50 128 0.26 575 170 79 72 56 950° C. × 4h 750 400 50 135 0.23 585 175 77 71 57 950° C. × 4 h 750 380 80 158 0.16700 220 51 64 58 950° C. × 4 h 750 400 80 150 0.24 610 185 69 70 59 950°C. × 4 h 750 420 50 145 0.40 530 155 85 74 60 920° C. × 8 h 720 400 50125 0.25 570 170 80 72 61 950° C. × 4 h 750 380 50 141 0.18 640 195 6267 Comparative 62 950° C. × 1 h 780 420 50 115 0.42 485 140 88 77example 63 880° C. × 8 h 720 400 50 104 0.36 490 145 87 76 64 970° C. ×4 h 820 400 50 125 0.55 545 160 80 76 65 920° C. × 4 h 680 400 50 1170.52 480 140 88 78 66 950° C. × 4 h 750 450 50 133 0.58 485 140 87 77 67950° C. × 4 h 750 400 5 116 0.54 475 135 88 78 68 950° C. × 4 h 750 40050 116 0.53 480 140 85 77 69 950° C. × 4 h 750 400 50 118 0.38 495 14583 76 70 950° C. × 4 h 750 400 50 115 0.35 490 145 85 76 71 950° C. × 4h 750 400 50 — — — — — —

indicates data missing or illegible when filed

Example 4

An example of the present invention will be described below. Cu—Fe—Palloy thin sheets having various contents of C, O, and H were producedby changing melting temperatures in an air melting furnace, and averagecooling rates (solidification rates) from the start of casting to 600°C. In each copper alloy thin sheet, the tensile strength, the hardness,the electric conductivity, and the platability or the like wereevaluated. These results are illustrated in Table 8.

Specifically, each of the copper alloys having each componentcomposition illustrated in Table 7 was ingoted by changing the meltingtemperatures, and the average cooling rates from the start of casting to600° C. as illustrated in Table 8. Melting was performed by using acoreless furnace that is an air melting furnace, and ingots with theirsizes of 70 mm in thickness×200 mm in width×500 mm in length wereproduced in the semi-continuous casting process.

After the surface of each ingot was subjected to facing and a heattreatment, sheets with a thickness of 16 mm were prepared by beingsubjected to the hot-rolling at a temperature of 950° C., which werequenched in water from a temperature of 750° C. or more. The oxidizedscale was removed, and thereafter the primary cold-rolling (intermediaterolling) was performed. The resulting sheet was subjected to facing andthe final cold-rolling in which 4 passes of cold-rolling with theintermediate annealing therebetween, were performed, and thereaftersubjected to the final low-temperature annealing at a temperature of350° C. for 20 seconds, allowing a copper alloy sheet with a thicknessof 0.15 mm to be obtained, the sheet corresponding to the thinning oflead frames.

In each copper alloy sheet illustrated in Table 7, the remaining elementother than the described elements is Cu, and as other impurity elements,a total content of Hf, Th, Li, Na, K, Sr, Pd, W, Si, Nb, Al, V, Y, Mo,In, Ga, Ge, As, Sb, Bi, Te, B, and misch metal was less than 0.1 mass %.

In the case where one or more elements selected from Mn, Mg, and Ca werecontained, a total content thereof was to be within the range of 0.0001to 1.0 mass %; and in the case where one or more elements selected fromZr, Ag, Cr, Cd, Be, Ti, Co, Ni, Au, and Pt were contained, a totalcontent thereof was to be within the range of 0.001 to 1.0 mass %; andfurther a total content of these whole elements was to be 1.0 mass % orless.

An O content was determined by extracting O in a sample with an inertgas fusion method and by analyzing the O with a combustion-infraredabsorption method, with the use of EMGA-650A tester made by HORIBA, Ltd.in accordance with JIS Z2613. An H content was determined by extractingH in a sample with an inert gas fusion method and by analyzing the Hwith a thermal conductivity method, with the use of RH-402 tester madeby LECO Corporation, in accordance with JIS Z2614. A C content wasdetermined by extracting C in a sample by heating the sample in oxygenatmosphere and by analyzing the C with a combustion-infrared absorptionmethod, with the use of EMIA 610 tester made by HORIBA, Ltd. inaccordance with JIS Z2615.

In each example, a sample was taken from each copper alloy sheet thusobtained, and the tensile strength, the hardness, the electricconductivity, the platability or the like of each sample, wereevaluated. These results are illustrated in Table 8.

(Evaluation of Platability)

In each copper alloy sheet, a sample with a size of 25 mm×60 mm wastaken from the obtained copper alloy sheet, and subsequently the samplewas plated with Ag in which the actual plating process for plating leadframes was simulated. Thereafter, the front and back face of the platedface were observed within the range of 10 cm² near the center of thesample, respectively, with the use of a stereo microscope (×40), suchthat the number of the unusual precipitations (projections) of theplating occurring within the above range was measured, the unusualprecipitation being observed as a projection of the plated layer asillustrated in FIG. 3. The case where the occurrence number was lessthan 2 per cm² was evaluated as good, while the case where theoccurrence number is 2 or more per cm² was evaluated as bad, becausethere was a fear that a bonding defect could be induced, and thereforecould not be used as a lead frame. The above Ag plating was performedafter the front and back face of a sample that had been subjected to apretreatment such as electrolytic degreasing, acid pickling, and watercleaning, was subjected to Cu basic electroplating in a commerciallyavailable Cu plating solution bath. The Cu basic plating was performedunder the conditions as follows: temperature is 60 to 65° C.; currentdensity is 5 A/dm²; and processing time is 10 seconds. The Agelectroplating was performed under the conditions as follows:temperature is 60 to 65 ° C.; current density is 7 A/dm²; and processingtime is 60 seconds.

(Measurement of Hardness)

Hardness of the copper alloy sheet sample was measured at 3 points ofthe sample with a micro Vickers hardness tester, by applying a load of0.5 kg, and an average value thereof was taken as the hardness of thesample.

(Measurement of Electric Conductivity)

After the copper alloy sheet sample was processed into a slip-shapedtest piece with a size of 10 mm in width ×300 mm in length by millingand an electric resistance thereof was measured with a double bridgeresistance meter, the electric conductivity thereof was calculated by anaverage cross-sectional area method.

As is clear from Tables 7 and 8, each of Inventive Examples 81 to 95that are copper alloys having component composition within the rangespecified by the present invention, is produced under the conditions inwhich a melting temperature of the melt in an air melting furnace, andan average cooling rate from the start of casting to 600° C., areproper. Accordingly, the contents of C as well as Fe and P are withinthe range specified by the present invention.

As a result, each of Inventive Examples 81 to 95 has a relatively highelectric conductivity for the high strength in which the tensilestrength is 500 MPa or more and the hardness is 150 Hv or more, and alsohas the excellent platability, even when O and H are present to someextent.

On the other hand, either of Comparative Examples 96 and 97 is producedunder the conditions in which a melting temperature in an air meltingfurnace is too low, or an average cooling rate from the start of castingto 600° C. is too small, and a C content is too small. As a result,either of Comparative Examples 96 or 97 has the decreased platability ascompared to Inventive Examples, while the contents of O and H are withinthe range specified by the present invention.

The contents of O and H of either of Comparative Examples 98 and 99 aretoo large. As a result, either of Comparative Examples 98 or 99 has theremarkably decreased strength and platability as compared to InventiveExamples 84 and 85 that have likewise high contents of O and H which areat the high level of the range, despite a large C content .

In Comparative Example 100, an Fe content is too small. Therefore,Comparative Example 100 has the decreased strength and hardness, while aC content is within the range specified by the present invention and hasthe excellent platability.

In the copper alloy of Comparative Example 101, an Fe content is toolarge. Therefore, Comparative Example 101 has the decreased strength,hardness, and electric conductivity, while a C content is within therange specified by the present invention.

In Comparative Example 102, a P content is too small. Therefore,Comparative Example 102 has the decreased strength, hardness, andelectric conductivity, while a C content is within the range specifiedby the present invention and has the excellent platability.

In the copper alloy of Comparative Example 103, a P content is toolarge. Therefore, a crack occurred at the end of the sheet during thehot-rolling.

In Comparative Example 104, the melting temperature in an air meltingfurnace is high and a C content is too large. As a result, ComparativeExample 104 has the decreased platability as compared to InventiveExamples, while the contents of O and H are within the range specifiedby the present invention.

From the above results, the critical importance of the C content or thelike in order to make the high strength compatible with the excellentplatability by which the unusual precipitation of the plating isprevented, can be supported; and the importance of the preferredproduction conditions for obtaining such structure, can also besupported.

TABLE 7 Component composition of copper alloy sheet (Remainder

 Cu and Alloy impurities: mass

, however with respect to C, O, H, S, and Pb, ppm) Classification No. FeP Zn Sn C O H S Pb Others Inventive 81 0.29 0.

1 0.29 0.020 3 9 0.4 10 7 — example 82 0.29 0.

1 0.29 0.020 8 12 0.3 8 12 — 83 0.29 0.12 0.29 0.56 8 13 0.2 8 9 — 840.33 0.12 0.60 0.025 10 40 0.2 6 5 — 85 0.27 0.09 0.10 1.0 10 8 1.0 7 7— 86 0.05 0.10 — — 7 12 0.3 8 14 — 87 0.46 0.

1 — — 7 10 0.3 12 8 — 88 0.29 0.027 — — 8 14 0.2 7 12 — 89 0.29 0.

4 — — 6 9 0.4 10 6 — 90 0.29 0.

1 0.29 0.020 8 12 0.2 8 10 Co: 0003 91 0.29 0.

1 0.29 0.020 8 10 0.2 8 8 Ca: 0.002, Ti: 0.005 92 0.29 0.

1 0.29 0.020 6 12 0.2 8 7 Mn: 0.003, Ni: 0.01, Au: 0.1 93 0.29 0.

1 0.29 0.020 7 10 0.3 10 7 Mg: 0.003, Ag: 0.1 94 0.29 0.

1 0.29 0.020 7 8 0.4 9 7 Ca: 0.002, Zr: 0.005 95 0.40 0.

4 0.30 0.020 12 15 0.3 8 10 — Comparative 96 0.29 0.

1 0.29 0.020 2 9 0.3 7 11 — example 97 0.29 0.

2 0.29 0.56 2 73 0.2 10 10 — 98 0.33 0.

2 0.29 0.020 10 45 0.2 6 8 — 99 0.33 0.

2 0.29 0.020 10 7 1.2 10 7 — 100 0.005 0.

0 0.27 0.025 4 15 0.2 8 10 — 101 0.56 0.

0 0.27 0.025 6 12 0.2 8 7 — 102 0.29 0.005 0.28 0.025 4 16 0.2 8 7 — 1030.29 0.

7 0.28 0.025 7 11 0.3 8 9 — 104 0.45 0.

4 0.29 0.020 17 20 0.3 10 10 — ′ Representations of each elementcontent, “—” represents below minimum detectable quantity

indicates data missing or illegible when filed

TABLE 8 Melting and casting conditions Average cooling rate from theProperties of copper alloy sheet Alloy Melting start of casting TensileHard- Electric Alloy No. in temperature to 600° C. strength nessconductivity Classification No. Table 1 ° C. ° C./s MPa Hv % IACSPlatability Inventive 81 81 1320 5.5 540 160 80 ∘ example 82 82 1330 6.0570 170 75 ∘ 83 83 1330 6.0 690 210 51 ∘ 84 84 1360 5.5 550 165 78 ∘ 8585 1360 6.0 675 205 50 ∘ 86 86 1320 6.0 525 155 84 ∘ 87 87 1320 6.0 580175 73 ∘ 88 88 1320 6.0 510 150 86 ∘ 89 89 1320 6.0 595 180 70 ∘ 90 901330 6.0 575 175 75 ∘ 91 91 1330 6.0 565 170 77 ∘ 92 92 1330 6.0 580 17573 ∘ 93 93 1330 6.0 585 180 72 ∘ 94 94 1330 6.0 570 170 76 ∘ 95 95 13806.0 625 190 65 ∘ Comparative 96 96 1250 6.0 570 170 75 x example 97 971310 4.0 560 165 77 x 98 98 1360 3.5 480 140 87 x 99 99 1360 4.0 490 14585 x 100 100 1330 6.0 470 140 88 ∘ 101 101 1330 6.0 490 145 84 x 102 1021330 6.0 460 135 89 ∘ 103 103 1330 6.0 — — — — 104 104 1400 6.0 610 18568 x

The present invention has been described in detail and with reference tothe specific embodiments, and it is clear to a person skilled in the artthat various modifications and variations can be made without departingfrom the spirit and the scope of the present invention. The presentinvention is based on Japanese Unexamined Patent Application (No.2006-270918) filed Oct. 2, 2006, Japanese Unexamined Patent Application(No.2006-274309) filed Oct. 5, 2006, Japanese Unexamined PatentApplication (No. 2006-311899) filed Nov. 17, 2006, and JapaneseUnexamined Patent Application (No. 2006-3111900) filed Nov. 17, 2006,the contents of which are incorporated herein by reference.

INDUSTRIAL APPLICABILITY

As stated above, according to the present invention, a Cu—Fe—P alloysheet with the high strength that is also provided with the excellentresistance peel off of oxidation film, which is compatible with the highstrength, can be provided. As a result, a semiconductor base material inwhich the adhesion between the resin and the die pad is high inassembling a semiconductor package, and therefore the reliability of thepackage is high, can be provided. Accordingly, the Cu—Fe—P alloy sheetaccording to the invention can be used in applications in which the highstrength, and the high resistance of peel off of oxidation film or thehigh reliability of packages, are needed, such as lead frames,connectors, terminals, switches, and relays, as well as lead frames forsemiconductor devices, as a material used for miniaturized andlightweight electric and electronic parts.

According to the present invention, a Cu—Fe—P alloy sheet with the highstrength that is also provided with the excellent bendability, which iscompatible with the high strength, can be provided. As a result, asemiconductor base material with the high reliability can be provided.Accordingly, the Cu—Fe—P alloy sheet according to the invention can beused in applications in which the high strength, and the high resistanceof peel off of oxidation film or the high reliability of packages, areneeded, such as lead frames, connectors, terminals, switches, andrelays, as well as lead frames for semiconductor devices, as a materialused for miniaturized and lightweight electric and electronic parts.

According to the present invention, a Cu—Fe—P alloy sheet with the highstrength that is also provided with the excellent stampability, which iscompatible with the high strength, can be provided. As a result, theCu—Fe—P alloy sheet according to the present invention can be used inapplications in which the high strength and the strict bendability areneeded, such as lead frames, connectors, terminals, switches, andrelays, as well as lead frames for semiconductor devices, as a materialused for miniatuarized and lightweight electric and electronic parts.

Moreover, according to the present invention, a Cu—Fe—P alloy sheet withthe high strength that is also provided with the excellent platability,which is compatible with the high strength, can be provided. As aresult, the Cu—Fe—P alloy sheet according to the present invention canbe used in applications in which the high strength and the strictbendability are needed, such as lead frames, connectors, terminals,switches, and relays, as well as lead frames for semiconductor devices,as a material used for miniaturized and lightweight electric andelectronic parts.

1. A copper alloy sheet comprising: 0.01 to 0.50 mass % of Fe; 0.01 to0.15 mass % of P; and a remainder being Cu and inevitable impurities,wherein the copper alloy sheet has a tensile strength of 500 MPa or moreand a hardness of 150 Hv or more, and wherein an r value parallel to arolling direction of the copper alloy sheet is 0.3 or more.
 2. Thecopper alloy sheet of claim 1, wherein the r value is 0.35 or more. 3.The copper alloy sheet of claim 2, wherein the r value is 0.5 or less.4. The copper alloy sheet of claim 1, wherein Fe is included in anamount of 0.15 to 0.35 mass %.
 5. The copper alloy sheet of claim 1,wherein P is included in an amount of 0.05 to 0.12 mass %.
 6. The copperalloy sheet of claim 1, wherein the copper alloy sheet further comprises0.005 to 5.0 mass % of Sn.
 7. The copper alloy sheet of claim 1, whereinthe copper alloy sheet further comprises 0.005 to 3.0 mass % of Zn. 8.The copper alloy sheet of claim 1, wherein contents of S and Pb in thecopper alloy sheet are each adjusted to be 20 ppm or less.
 9. The copperalloy sheet of claim 1, further comprising: a total content of 0.0001 to1.0 mass % of one or more elements selected from the group consisting ofMn, Mg, and Ca.
 10. The copper alloy sheet of claim 1, furthercomprising: a total content of 0.001 to 1.0 mass % of one or moreelements selected from the group consisting of Zr, Ag, Cr, Cd, Be, Co,Ni, Au, and Pt.
 11. The copper alloy sheet of claim 1, furthercomprising: a total content of 0.0001 to 1.0 mass % of at least onefirst element selected from the group consisting of Mn, Mg, and Ca; anda total content of 0.001 to 1.0 mass % of at least one second elementselected from the group consisting of Zr, Ag, Cr, Cd, Be, Ti, Co, Ni,Au, and Pt, wherein a total content of the first and second elements is1.0 mass % or less.
 12. The copper alloy sheet of claim 1, wherein thecopper alloy sheet comprises a total content of 0.1 mass % or less ofHf, Th, Li, Na, K, Sr, Pd, W, S, Si, C, Nb, Al, V, Y, Mo, Pb, In, Ga,Ge, As, Sb, Bi, Te, B, and misch metal.